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Karcher, René. "Virtualisierte DMZ auf Xen-Basis OpenQRM und Xen als Partner." Hamburg Diplomica-Verl, 2007. http://d-nb.info/989529673/04.
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Karcher, René. "Virtualisierte DMZ auf Xen-Basis : OpenQRM und Xen als Partner /." Hamburg : Diplomica Verl, 2008. http://www.diplom.de/katalog/arbeit/11199.
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Hnarakis, Ryan. "In Perfect Xen, A Performance Study of the Emerging Xen Scheduler." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1121.
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Fifty percent of Fortune 500 companies trust Xen, an open-source bare-metal hypervisor, to virtualize their websites and mission critical services in the cloud. Providing superior fault tolerance, scalability, and migration, virtualization allows these companies to run several isolated operating systems simultaneously on the same physical server. These isolated operating systems, called virtual machines, require a virtual traffic guard to cooperate with one another. This guard known as the Credit2 scheduler along with the newest Xen hypervisor was recently developed to supersede the older schedulers. Since wasted CPU cycles can be costly, the Credit2 prototype must undergo significant performance validation before being released into production. Furthermore, leading commercial virtualization products, including VMWare and Microsoft Hyper-V frequently adopt Xen's proven technologies. This thesis provides quantitative performance measurements of the Credit1 and Credit2 schedulers, and provides recommendations for building hypervisor schedulers.
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Bjerke, Håvard K. F. "HPC Virtualization with Xen on Itanium." Thesis, Norwegian University of Science and Technology, Department of Computer and Information Science, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9263.
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<p>The Xen Virtual Machine Monitor has proven to achieve higher efficiency in virtualizing the x86 architecture than competing x86 virtualization technologies. This makes virtualization on the x86 platform more feasible in High-Performance and mainframe computing, where virtualization can offer attractive solutions for managing resources between users. Virtualization is also attractive on the Itanium architecture. Future x86 and Itanium computer architectures include extensions which make virtualization more efficient. Moving to virtualizing resources through Xen may ready computer centers for the possibilities offered by these extensions. The Itanium architecture is ``uncooperative'' in terms of virtualization. Privilege-sensitive instructions make full virtualization inefficient and impose the need for para-virtualization. Para-virtualizing Linux involves changing certain native operations in the guest kernel in order to adapt it to the Xen virtual architecture. Minimum para-virtualizing impact on Linux is achieved by, instead of replacing illegal instructions, trapping them by the hypervisor, which then emulates them. Transparent para-virtualization allows the same Linux kernel binary to run on top of Xen and on physical hardware. Itanium region registers allow more graceful distribution of memory between guest operating systems, while not disturbing the Translation Lookaside Buffer. The Extensible Firmware Interface provides a standardized interface to hardware functions, and is easier to virtualize than legacy hardware interfaces. The overhead of running para-virtualized Linux on Itanium is reasonably small and measured to be around 4.9 %. Also, the overhead of running transparently para-virtualized Linux on physical hardware is reasonably small compared to non-virtualized Linux.</p>
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Rossi, Fábio Diniz. "Alocação dinâmica de recursos no Xen." Pontifícia Universidade Católica do Rio Grande do Sul, 2008. http://hdl.handle.net/10923/1484.
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Previous issue date: 2008<br>The demand for computer processing power has increased in the past years, resulting in computers that provide such capacity. Sometimes different approaches have also being developed to improve computing power by joining together a set of computers, for example in clusters of computers. Currently we have access to this type of solutions but we do not use all their computing power the best way we could. This may lead to a situation in which resources are being wasted. In order to avoid the waste of computing resources, lately the use of virtual machines have been widely used. A virtual machines is a software layer that creates an environment in which several systems can be executed as if they had their own private computer. One solution that allows this approach is Xen. Xen is a paravirtualizer that allows several different operating systems to run as if they were using different computers. The scheduling of the different operating systems that are running in the same computer is performed by one of three possible strategies provided by Xen. The standard scheduler is called "SMP Credit Scheduler", which is recommended when running Xen on multiprocessing computers because it allows load balancing among virtual and real processors. Despite being the best current Xen scheduler, the SMP Credit Scheduler still does not fully use the computing power of a machine. This work proposes to improve the use of the machine by the operating systems (virtual machines) that are running on Xen. We propose a system that dynamically changes the configuration of the virtual machines. Our system will reallocate resources that are not being used by a virtual machine to a virtual machine that needs more resources.<br>A demanda por poder computacional é cada vez maior, e conseqüentemente leva ao desenvolvimento de equipamentos com capacidades de processamento cada vez maiores para suprí-la. Hoje em dia temos acesso a computadores com poder computacional cada vez maior, porém em sua grande maioria, esse poder computacional é apenas parcialmente utilizado, causando uma ociosidade dos recursos disponíveis, o que pode acarretar aumento de custos. Ao analisarmos a situação do aumento do poder computacional, a idéia de ociosidade de processamento da maioria dos computadores e em contrapartida, a possibilidade de uma melhor utilização de recursos, podemos explicar a renovação de tecnologias que podem vir a suprir essas necessidades. Entre várias destas tecnologias podemos citar clusters e grades computacionais, e entre outras, uma das tecnologias em ascensão são as máquinas virtuais. Uma máquina virtual consiste em um software que cria um ambiente sobre um sistema operacional, possibilitando uma execução abstraída do hardware de vários outros sistemas, sendo transparente para o usuário essa interação. Dentre vários ambientes que suportam o uso de máquinas virtuais, utilizamos o Xen que proporciona a portabilidade de sistemas operacionais sobre um sistema operacional Linux e permite compartilhar uma simples máquina para vários clientes rodando sistemas operacionais distintos. O Xen pode utilizar um de três escalonadores, onde o SMP Credit Scheduler é o escalonador padrão, recomendado para máquinas multiprocessadas por permitir balanceamento de processadores virtuais entre os processadores reais. Porém, o SMP Credit Scheduler ainda tem algumas limitações referentes a uma utilização melhor dos recursos da máquina. Com o objetivo de superar algumas dessas limitações, este trabalho apresenta a proposta e implementação de um subsistema que altera dinamicamente configurações do escalonador SMP Credit, realocando recursos destinados a máquinas virtuais que não estejam utilizando todo o processamento disponível, direcionado-as às máquinas virtuais que necessitem desse processamento. Por fim, apresentamos uma avaliação do uso desse subsistema frente ao escalonador SMP Credit em diversas configurações possíveis.
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Özcan, Mehmet Batuhan, and Gabriel Iro. "PARAVIRTUALIZATION IMPLEMENTATION IN UBUNTU WITH XEN HYPERVISOR." Thesis, Blekinge Tekniska Högskola, Institutionen för kommunikationssystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2011.
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With the growing need for efficiency, cost reduction, reduced disposition of outdated electronics components as well as scalable electronics components, and also reduced health effects of our daily usage of electronics components. Recent trend in technology has seen companies manufacturing these products thinking in the mentioned needs when manufacturing and virtualizations is one important aspect of it. The need to share resources, the need to use lesser workspace, the need to reduce cost of purchase and manufacturing are all part of achievements of virtualization techniques. For some people, setting up a computer to run different virtual machines at the same time can be difficult especially if they have no prior basic knowledge of working in terminal environment and hiring a skilled personnel to do the job can be expensive. The motivation for this thesis is to help people with little or no basic knowledge on how to set up virtual machine with Ubuntu operating system on XEN hypervisor.
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Kanthla, Arjun Reddy. "Network Performance Improvement for Cloud Computing using Jumbo Frames." Thesis, KTH, Radio Systems Laboratory (RS Lab), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-143806.
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The surge in the cloud computing is due to its cost effective benefits and the rapid scalability of computing resources, and the crux of this is virtualization. Virtualization technology enables a single physical machine to be shared by multiple operating systems. This increases the eciency of the hardware, hence decreases the cost of cloud computing. However, as the load in the guest operating system increases, at some point the physical resources cannot support all the applications efficiently. Input and output services, especially network applications, must share the same total bandwidth and this sharing can be negatively affected by virtualization overheads. Network packets may undergo additional processing and have to wait until the virtual machine is scheduled by the underlying hypervisor before reaching the final service application, such as a web server.In a virtualized environment it is not the load (due to the processing of the user data) but the network overhead, that is the major problem. Modern network interface cards have enhanced network virtualization by handling IP packets more intelligently through TCP segmentation offload, interrupt coalescence, and other virtualization specific hardware. Jumbo frames have long been proposed for their advantages in traditional environment. They increase network throughput and decrease CPU utilization. Jumbo frames can better exploit Gigabit Ethernet and offer great enhancements to the virtualized environment by utilizing the bandwidth more effectively while lowering processor overhead. This thesis shows a network performance improvement of 4.7% in a Xen virtualized environment by using jumbo frames. Additionally the thesis examines TCP's performance in Xen and compares Xen with the same operations running on a native Linux system.<br>Den kraftiga ökningen i datormoln är på grund av dess kostnadseffektiva fördelar och den snabba skalbarhet av datorresurser, och kärnan i detta är virtualisering. Virtualiseringsteknik möjliggör att man kan köra era operativsystem på en enda fysisk maskin. Detta ökar effektiviteten av hårdvaran, vilket gör att kostnaden minskar för datormoln. Men eftersom lasten i gästoperativsystemet ökar, gör att de fysiska resurserna inte kan stödja alla program på ett effektivt sätt. In-och utgångstjänster, speciellt nätverksapplikationer, måste dela samma totala bandbredd gör att denna delning kan påverkas negativt av virtualisering. Nätverkspaket kan genomgå ytterligare behandling och måste vänta tills den virtuella maskinen är planerad av den underliggande hypervisor innan den slutliga services applikation, till exempel en webbserver. I en virtuell miljö är det inte belastningen (på grund av behandlingen av användarens data) utan nätverket overhead, som är det största problemet. Moderna nätverkskort har förbättrat nätverk virtualisering genom att hantera IP-paket mer intelligent genom TCP- segmenterings avlastning, avbrotts sammansmältning och genom en annan hårdvara som är specifik för virtualisering. Jumboramar har länge föreslagits för sina fördelar i traditionell miljö. De ökar nätverk genomströmning och minska CPU-användning. Genom att använda Jumbo frames kan Gigabit Ethernet användandet förbättras samt erbjuda stora förbättringar för virtualiserad miljö genom att utnyttja bandbredden mer effektivt samtidigt sänka processor overhead. Det här examensarbetet visar ett nätverk prestandaförbättring på 4,7% i en Xen virtualiserad miljö genom att använda jumbo frames. Dessutom undersöker det TCP prestanda i Xen och jämför Xen med samma funktion som körs på en Linux system.
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Rossi, F?bio Diniz. "Aloca??o din?mica de recursos no Xen." Pontif?cia Universidade Cat?lica do Rio Grande do Sul, 2008. http://tede2.pucrs.br/tede2/handle/tede/5039.
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Previous issue date: 2008-01-15<br>A demanda por poder computacional ? cada vez maior, e conseq?entemente leva ao desenvolvimento de equipamentos com capacidades de processamento cada vez maiores para supr?-la. Hoje em dia temos acesso a computadores com poder computacional cada vez maior, por?m em sua grande maioria, esse poder computacional ? apenas parcialmente utilizado, causando uma ociosidade dos recursos dispon?veis, o que pode acarretar aumento de custos. Ao analisarmos a situa??o do aumento do poder computacional, a id?ia de ociosidade de processamento da maioria dos computadores e em contrapartida, a possibilidade de uma melhor utiliza??o de recursos, podemos explicar a renova??o de tecnologias que podem vir a suprir essas necessidades. Entre v?rias destas tecnologias podemos citar clusters e grades computacionais, e entre outras, uma das tecnologias em ascens?o s?o as m?quinas virtuais. Uma m?quina virtual consiste em um software que cria um ambiente sobre um sistema operacional, possibilitando uma execu??o abstra?da do hardware de v?rios outros sistemas, sendo transparente para o usu?rio essa intera??o. Dentre v?rios ambientes que suportam o uso de m?quinas virtuais, utilizamos o Xen que proporciona a portabilidade de sistemas operacionais sobre um sistema operacional Linux e permite compartilhar uma simples m?quina para v?rios clientes rodando sistemas operacionais distintos. O Xen pode utilizar um de tr?s escalonadores, onde o SMP Credit Scheduler ? o escalonador padr?o, recomendado para m?quinas multiprocessadas por permitir balanceamento de processadores virtuais entre os processadores reais. Por?m, o SMP Credit Scheduler ainda tem algumas limita??es referentes a uma utiliza??o melhor dos recursos da m?quina. Com o objetivo de superar algumas dessas limita??es, este trabalho apresenta a proposta e implementa??o de um subsistema que altera dinamicamente configura??es do escalonador SMP Credit, realocando recursos destinados a m?quinas virtuais que n?o estejam utilizando todo o processamento dispon?vel, direcionado-as ?s m?quinas virtuais que necessitem desse processamento. Por fim, apresentamos uma avalia??o do uso desse subsistema frente ao escalonador SMP Credit em diversas configura??es poss?veis
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Singh, Jaswinder. "Performance evaluation of Linux Bridge and OVS in Xen." Thesis, Blekinge Tekniska Högskola, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-10825.
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Virtualization is the key technology which has provided smarter and easier ways for effectively utilizing resources provided by the hypervisor. Virtualization allows multiple operative systems (OS) to run on a single hardware. The resources from a hardware are allocated to virtual machines (VM) by hypervisor. It is important to know how the performance of virtual switches used in hypervisor for network communication affect the network traffic. Performance of Linux Bridge (LB) and Open vSwitch (OVS) is investigated in this study. The method that has been used in this research is experimentation. Two different scenarios are used to benchmark the performance of LB and OVS in virtual and non-virtual environment. Performance metrics bitrate is used to benchmark the performance LB and OVS. The results received from the experimental runs contains the ingress bitrate and egress bitrate of LB and OVS in virtual and non-virtual environment. The results also contain the ingress and egress bitrate values from scenarios with different memory and CPU cores in virtual environment. Results achieved in this thesis report are from multiple experiment configurations. From results it can concluded that LB and OVS have almost same performance in non-virtual environment. There are small differences in ingress and egress of both virtual switches.
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Härtel, René. "Virtualisierung und Netzwerkinfrastruktur - Untersuchung des Aufbaus eines Xen-Clusters." Thesis, Universitätsbibliothek Chemnitz, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200900482.
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Diese Arbeit beschäftigt sich mit dem Aufbau und der
Konfiguration eines XEN-basierten Clusters am
Beispiel der RedHat Cluster Suite (RHCS).
Es werden Lösungsmöglichkeiten für den Betrieb
virtueller Gastsysteme mit unterschiedlichen
Subnetzen (VLANs) im Cluster aufgezeigt. Zudem
werden Möglichkeiten zur Umsetzung von
HA-Eigenschaften des Netzwerkes im Cluster
untersucht. (NIC-Bonding)
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Outadi, Siavash, and Jana Trchalikova. "Performance comparison of KVM and XEN for telecommunication services." Thesis, Blekinge Tekniska Högskola, Institutionen för datalogi och datorsystemteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2552.
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High stability of telecommunication services has a positive e ect on customer satisfaction and thus helps to maintain competitiveness of the product in telecommunication market. Since live migration provides a minimal down- time of virtual machines, it is deployed by telecommunication companies to ensure high availability of services and to prevent service interruptions. The main objective of this research is to assess the performance of various hypervisors in terms of live migration and determine which of them best meets the criteria given by a telecommunication company. Response time and CPU utilization of telecommunication services are measured in non- virtualized and virtualized environments to better understand the impacts of virtualization on the services. Two hypervisors, i.e. KVM and XEN, are used to grasp their characteristic behaviour of handling the services. Furthermore, performance of live migration is assessed for both hypervisors using miscellaneous test cases to identify which one has the best overall performance in terms of downtime and total migration time.
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Wilcox, Terry Clyde. "Dynamic load balancing of virtual machines hosted on Xen /." Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd2755.pdf.
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Wilcox, Terry Clyde. "Dynamic Load Balancing of Virtual Machines Hosted on Xen." BYU ScholarsArchive, 2008. https://scholarsarchive.byu.edu/etd/1654.
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Currently systems of virtual machines are load balanced statically which can create load imbalances for systems where the load changes dynamically over time. For throughput and response time of a system to be maximized it is necessary for load to be evenly distributed among each part of the system. We implement a prototype policy engine for the Xen virtual machine monitor which can dynamically load balance virtual machines. We compare the throughput and response time of our system using the cpu2000 and the WEB2005 benchmarks from SPEC. Under the loads we tested, dynamic load balancing had 5%-8% higher throughput than static load balancing.
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Lindholm, Rickard. "Analysis of Resource Isolation and Resource Management in Network Virtualization." Thesis, Blekinge Tekniska Högskola, Institutionen för kommunikationssystem, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-11740.
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Context. Virtualized networks are considered a major advancement in the technology of today, virtualized networks are offering plenty of functional benefits compared to todays dedicated networking elements. The virtualization allows network designers to separate networks and adapting the resources depending on the actual loads in other words, Load Balancing. Virtual networks would enable a minimized downtime for deployment of updates and similar tasks by performing a simple migration and then updating the linking after properly testing and preparing the Virtual Machine with the new software. When this technology is successfully proven to be efficient or evaluated and later adapted to the existing flaws. Virtualized networks will at that point claim the tasks of todays dedicated networking elements. But there are still unknown behaviors and effects of the technology for example, how the scheduler or hypervisor handles the virtual separation since they do share the same physical transmission resources.Objectives. By performing the experiments in this thesis, the hope is to learn about the effects of virtualization and how it performs under stress. By learning about the performance under stress it would also increase the knowledge about the efficiency of network virtualization. The experiments are conducted by creating scripts, using already written programs and systems, adding different loads and measuring the effects, this is documented so that other students and researchers can benefit from the research done in this thesis.Methods. In this thesis 5 different methodologies are performed: Experimental validation, statistical comparative analysis, resource sharing, control theory and literature review. Two systems are compared to previous research by evaluating the statistical results and analyzing them. As mentioned earlier the investigation of this thesis is focusing on how the scheduler executes the resource sharing under stress. The first system which is the control test is designed without any interference and a 5 Mbit/s UDP stream which is going through the system under test and being timestamped on measurement points on both the ingress and the egress, the second experiment involves an interfering load of a 5 Mbit/s UDP stream on the same system under test. Since it is a complex system quite some literature reviewing was done but mostly to gain a understanding and an overview of the different parts of the system and so that some obstacles would be able to be avoided.Results. The statistical comparative analysis of the experiments produced two graphs and two tables containing the coefficient of variance of the two experiments. The graph of the control test produced a graph with a quite even distribution over the time intervals with a coefficient of variance difference to the power of 10−3 and increasing somewhat over the larger time intervals. The second experiment with two virtual machines and an interfering packet stream are more distributed over the 0.0025 seconds and the 0.005 seconds intervals with a larger difference than the control test having a difference to the power of 10−2, showing some signs of a bottleneck in the system.Conclusions. Since the performance of the experiments and also the statistical handling of the data took longer than expected the choice was made to not deploy the system using Open Virtual Switch instead of Linux Bridge, hence there is not any other experiments to compare the performance with. But from referred research under related works the researcher concluded that the difference between Open Virtual Switch and Linux Bridge is small when compared without introducing any load. This is also confirmed on the website of Open Virtual Switch which states that Open Virtual Switch uses the same base as Linux Bridge. Linux Bridge is performing according to the expectations, it is a simple yet powerful tool and the results are confirming the previous research which claims that there are bottlenecks in the system. According to the pre-set requirement for validity for this experiment the difference of the CoV would be greater than to the power of 10−5, the measured difference was to the power of 10−2 which gives support to the theory that there are bottlenecks in the system. In the future it would be interesting to examine more about the effects of different hypervisors, virtualization techniques, packet generators etcetera to tackle these problems. A company that have taken countermeasures is Intel who have developed DPDK which confronts these efficiency problems by tailoring the scheduler towards the specific tasks. The downside of Intel’s DPDK is that it limits the user to Intel processors and removes one of the most important benefits of virtualization, the independence. But Intel have tried to keep it as independent as possible by maintaining DPDK as open source.
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Sung, Mincheol. "Design and Implementation of a Network Server in LibrettOS." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/87066.
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Traditional network stacks in monolithic kernels have reliability and security concerns. Any fault in a network stack affects the entire system owing to lack of isolation in the monolithic kernel. Moreover, the large code size of the network stack enlarges the attack surface of the system. A multiserver OS design solves this problem. In contrast to the traditional network stack, a multiserver OS pushes the network stack into the network server as a user process, which performs three enhancements: (i) allows the network server to run in user mode while having its own address space and isolating any fault occurring in the network server; (ii) minimizes the attack surface of the system because the trusted computing base contracts; (iii) enables failure recovery, which is an important feature supported by a multiserver OS. This thesis proposes a network server for LibrettOS, an operating system based on rumprun unikernels and the Xen Hypervisor developed by Virginia Tech. The proposed network server is a service domain providing an L2 frame forwarding service for application domains and based on rumprun such that the existing device drivers of NetBSD can be leveraged with little modification. In this model, the TCP/IP stack runs directly in the address space of applications. This allows retaining the client state even if the network server crashes and makes it possible to recover from a network server failure. We leverage the Xen PCI passthrough to access a NIC (Network Interface Controller) from the network server. Our experimental evaluation demonstrates that the performance of the network server is good and comparable with Linux and NetBSD. We also demonstrate the successful recovery after a failure.<br>This research is based upon work supported by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA). The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the ODNI, IARPA, or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright annotation thereon.
This research is also based upon work supported by the Office of Naval Research (ONR) under grants N00014-16-1-2104, N00014-16-1-2711, and N00014-18-1-2022.<br>Master of Science<br>When it comes to reliability and security in networking systems, concerns have been shown in traditional operating systems (OSs) such as Windows, MacOS, NetBSD, and Linux. Any fault in a networking system can have impacts on the entire system owing to lack of isolation in the OSs. Moreover, the large code size of a networking system enlarges the attack surface of the system. A multiserver OS design solves this problem by running a networking system as a network server, which performs three enhancements: (i) isolates any fault occurring in the network server itself; (ii) minimizes the attack surface of the system; and (iii) enables failure recovery. This thesis proposes a network server for LibrettOS, an operating system developed by Virginia Tech. The proposed network has two-pronged merits: (i) provides a system server providing a network packet forwarding service for applications; (ii) enables the existing device drivers of NetBSD to be leveraged with low amount of modification. Our experimental evaluation demonstrates that the performance of the network server outperforms state-of-the-art and comparable with Linux and that a successful recovery is possible after a failure.
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Le, Cuong Hoang H. "Protecting xen hypercalls : intrusion detection/ prevention in a virtualization environment." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/14849.
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During the past few years virtualization has strongly reemerged from the shadow of the mainframe generation as a promising technology for the new generation of computers. Both the research and industry communities have recently looked at virtualization as a solution for security and reliability. With the increased usage and dependence on this technology, security issues of virtualization are becoming more and more relevant. This thesis looks at the challenge of securing Xen, a popular open source virtualization technology. We analyze security properties of the Xen architecture,
propose and implement different security schemes including authenticated
hypercalls, hypercall access table and hypercall stack trace verification to
secure Xen hypercalls (which are analogous to system calls in the OS world).
The security analysis shows that hypercall attacks could be a real threat to
the Xen virtualization architecture (i.e., hypercalls could be exploited to
inject malicious code into the virtual machine monitor (VMM) by a compromised guest OS), and effective hypercall protection measures can prevent this threat. The initial performance analysis shows that our security measures are efficient in terms of execution time and space.
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Silva, Marcelo Pereira da. "Adaptive Remus: replicação de máquinas virtuais Xen com checkpointing adaptável." Universidade do Estado de Santa Catarina, 2015. http://tede.udesc.br/handle/handle/2046.
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Previous issue date: 2015-07-03<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>With the ever-increasing dependence on computers and networks, many systems are required to be continuously available in order to fulfill their mission. Virtualization technology enables high availability to be offered in a convenient, cost-effective manner: with the encapsulation provided by virtual machines (VMs), entire systems can be replicated transparently in software, obviating the need for expensive fault-tolerant hardware. Remus is a VM replication mechanism for the Xen hypervisor that provides high availability despite crash failures. Replication is performed by checkpointing the VM at fixed intervals. However, there is an antagonism between processing and communication regarding the optimal checkpointing interval: while longer intervals benefit processorintensive applications, shorter intervals favor network-intensive applications. Thus, any chosen interval may not always be suitable for the hosted applications, limiting Remus usage in many scenarios. This work introduces Adaptive Remus, a proposal for adaptive checkpointing in Remus that dynamically adjusts the replication frequency according to the characteristics of running applications. Experimental results indicate that our proposal improves performance for applications that require both processing and communication, without harming applications that use only one type of resource.<br>Com a dependência cada vez maior de computadores e redes, muitos sistemas precisam estar continuamente disponíveis para cumprir sua missão. A tecnologia de virtualização permite prover alta disponibilidade de forma conveniente e a um custo razoável: com o encapsulamento oferecido pelas máquinas virtuais (MVs), sistemas inteiros podem ser replicados em software, de forma transparente, eliminando a necessidade de hardware tolerante a faltas dispendioso. Remus é um mecanismo de replicação de MVs que fornece alta disponibilidade diante de faltas de parada. A replicação é realizada através de checkpointing, seguindo um intervalo fixo de tempo predeterminado. Todavia, existe um antagonismo entre processamento e comunicação em relação ao intervalo ideal entre checkpoints: enquanto intervalos maiores beneficiam aplicações com processamento intensivo, intervalos menores favorecem as aplicações cujo desempenho é dominado pela rede. Logo, o intervalo utilizado nem sempre é o adequado para as características de uso de recursos da aplicação em execução na MV, limitando a aplicabilidade de Remus em determinados cenários. Este trabalho apresenta Adaptive Remus, uma proposta de checkpointing adaptativo para Remus, que ajusta dinamicamente a frequência de replicação de acordo com as características das aplicações em execução. Os resultados indicam que a proposta obtém um melhor desempenho de aplicações que utilizam tanto recursos de processamento como de comunicação, sem prejudicar aplicações que usam apenas um dos tipos de recursos.
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Antonioli, Rafael. "Detecção e tratamento de intrusões em plataformas baseadas no XEN." Pontifícia Universidade Católica do Rio Grande do Sul, 2008. http://hdl.handle.net/10923/1524.
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Previous issue date: 2008<br>Servers virtualization is a technology which became a solution to several demands of today’s computational systems: machines idles cycles, high energy consumption, physical space occupation issues and the difficult to management different operating systems in a same computational environment. Among the existing virtualization platforms, Xen appears as an interesting choice presenting the best performance in comparison with the remaining alternatives. Virtualized systems very often require security and one way to provide safe virtualized systems is through the use of intrusion detection systems which are able to monitor the network data traffic. This work presents an approach to detect intrusion in Xen virtual machines, introducing a tool to monitor and block malicious or unwanted access to the system. The tool was named XenGuardian and it works using direct communication between the virtual machine (DomU) and the host machine (Dom0) to indicate when a suspicious action is detected. If unauthorized access attempts are identified, the host machine deal with the situation blocking the user responsible for the attack. In order to validate XenGuardian efficiency, exploits were used to perform attacks against the intrusion detection system. Performance measures were obtained through the use of the NetPerf benchmark.<br>A virtualização de servidores aparece como uma solução para várias demandas atuais dos sistemas computacionais: taxa de ociosidade das máquinas, alto consumo de energia, ocupação de espaço físico e dificuldade para gerenciamento de muitos sistemas operacionais em um mesmo datacenter. Entre as alternativas de virtualização disponíveis, o monitor de máquina virtual Xen é uma das opções mais consolidadas e que possui melhor desempenho dentre as demais alternativas existentes. Para proporcionar sistemas virtualizados seguros, um aliado eficaz são os sistemas detectores de intrusão que trabalham realizando monitoração no tráfego da rede. Este trabalho apresenta uma abordagem para detecção de intrusão em máquinas virtuais baseadas no monitor de máquina virtual Xen, introduzindo uma ferramenta para detectar e bloquear intrusos que estiverem tentando obter acesso indevido ao sistema. A ferramenta elaborada recebeu o nome de XenGuardian e trabalha realizando comunicação entre as máquinas virtuais (domU) com a máquina hóspede (dom0). Na ocorrência de tentativas de acesso não autorizadas, a máquina hóspede realiza o tratamento da ocorrência bloqueando o usuário. Para validar a solução, exploits foram utilizados, desferindo ataques contra sistemas de detecção de intrusos e auferindo medições de desempenho através do benchmark NetPerf.
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Zhuang, Hao. "Performance Evaluation of Virtualization in Cloud Data Center." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-104206.
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Amazon Elastic Compute Cloud (EC2) has been adopted by a large number of small and medium enterprises (SMEs), e.g. foursquare, Monster World, and Netflix, to provide various kinds of services. There has been some existing work in the current literature investigating the variation and unpredictability of cloud services. These work demonstrated interesting observations regarding cloud offerings. However, they failed to reveal the underlying essence of the various appearances for the cloud services. In this thesis, we looked into the underlying scheduling mechanisms, and hardware configurations, of Amazon EC2, and investigated their impact on the performance of virtual machine instances running atop. Specifically, several instances with the standard and high-CPU instance families are covered to shed light on the hardware upgrade and replacement of Amazon EC2. Then large instance from the standard family is selected to conduct focus analysis. To better understand the various behaviors of the instances, a local cluster environment is set up, which consists of two Intel Xeon servers, using different scheduling algorithms. Through a series of benchmark measurements, we observed the following findings: (1) Amazon utilizes highly diversified hardware to provision different instances. It results in significant performance variation, which can reach up to 30%. (2) Two different scheduling mechanisms were observed, one is similar to Simple Earliest Deadline Fist (SEDF) scheduler, whilst the other one analogies Credit scheduler in Xen hypervisor. These two scheduling mechanisms also arouse variations in performance. (3) By applying a simple "trial-and-failure" instance selection strategy, the cost saving is surprisingly significant. Given certain distribution of fast-instances and slow-instances, the achievable cost saving can reach 30%, which is attractive to SMEs which use Amazon EC2 platform.<br>Amazon Elastic Compute Cloud (EC2) har antagits av ett stort antal små och medelstora företag (SMB), t.ex. foursquare, Monster World, och Netflix, för att ge olika typer av tjänster. Det finns en del tidigare arbeten i den aktuella litteraturen som undersöker variationen och oförutsägbarheten av molntjänster. Dessa arbetenhar visat intressanta iakttagelser om molnerbjudanden, men de har misslyckats med att avslöja den underliggande kärnan hos de olika utseendena för molntjänster. I denna avhandling tittade vi på de underliggande schemaläggningsmekanismerna och maskinvarukonfigurationer i Amazon EC2, och undersökte deras inverkan på resultatet för de virtuella maskiners instanser som körs ovanpå. Närmare bestämt är det flera fall med standard- och hög-CPU instanser som omfattas att belysa uppgradering av hårdvara och utbyte av Amazon EC2. Stora instanser från standardfamiljen är valda för att genomföra en fokusanalys. För att bättre förstå olika beteenden av de olika instanserna har lokala kluster miljöer inrättas, dessa klustermiljöer består av två Intel Xeonservrar och har inrättats med hjälp av olika schemaläggningsalgoritmer. Genom en serie benchmarkmätningar observerade vi följande slutsatser: (1) Amazon använder mycket diversifierad hårdvara för att tillhandahållandet olika instanser. Från de olika instans-sub-typernas perspektiv leder hårdvarumångfald till betydande prestationsvariation som kan nå upp till 30%. (2) Två olika schemaläggningsmekanismer observerades, en liknande Simple Earliest Deadline Fist(SEDF) schemaläggare, medan den andra mer liknar Credit-schemaläggaren i Xenhypervisor. Dessa två schemaläggningsmekanismer ger även upphov till variationer i prestanda. (3) Genom att tillämpa en enkel "trial-and-failure" strategi för val av instans, är kostnadsbesparande förvånansvärt stor. Med tanke på fördelning av snabba och långsamma instanser kan kostnadsbesparingen uppgå till 30%, vilket är attraktivt för små och medelstora företag som använder Amazon EC2 plattform.
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Anderson, Benjamin Robert. "Xen Worlds creating a virtual laboratory environment for use in education /." [Ames, Iowa : Iowa State University], 2010. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1476271.
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Cabrera, Peña Jacqueline. "Campamento de la Tortuga Marina de Carey en Punta Xen, Campeche." Tesis de Licenciatura, Universidad Autónoma del Estado de México, 2016. http://hdl.handle.net/20.500.11799/99862.
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El ecoturismo es una modalidad de turismo alternativo, en el que se practican actividades en contacto con la naturaleza, la practica ecoturística ha resultado ser una alternativa para la conservación del medio ambiente en México y en otras partes del mundo, lo cual contribuye a la generación de una derrama económica en donde se realiza, favoreciendo de este modo a la comunidad. Estas acciones se han convertido en una fuente de ingresos económicos alternativos para aquellas comunidades que viven en ambientes, de alta fragilidad.
La práctica del ecoturismo en México es posible gracias a la muy variada diversidad que posee en cuanto a flora y fauna; además el territorio nacional tiene diferentes biomas pues es factible encontrar desde selvas, bosques de diferentes tipos, hasta desiertos. Algunos de ellos son aptos para soportar la presencia humana y otros demasiados frágiles para visitarlos físicamente, debido a esta discrepancia en la fragilidad de los ecosistemas se ha definido cuál puede ser visitado y cuales deben permanecer intactos para su preservación.
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Zhang, Quan. "Impacts on the I/O performance of the virtual disk in Xen." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/39998.
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Storage systems are complicated, especially after the virtualization technology has been introduced. As is a key metric, the I/O throughput of the storage in the virtual machine environment is remarkably lower than that in the non-virtualized environment. This disparity should be alleviated because of the growing popularity of virtual machines.
In this paper, four factors, which affect the I/O throughput of the generic Linux storage subsystem and further degrade virtualization on this storage subsystem, are testified by quantitative approaches, leading to the effective solutions of improving the I/O throughput. The improvements are verified by experiments; however, the overhead of virtualization is inevitable. Therefore, a further way to offset the overhead is also given in this thesis.
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Antonioli, Rafael. "Detec??o e tratamento de intrus?es em plataformas baseadas no XEN." Pontif?cia Universidade Cat?lica do Rio Grande do Sul, 2008. http://tede2.pucrs.br/tede2/handle/tede/5025.
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Previous issue date: 2008-03-28<br>A virtualiza??o de servidores aparece como uma solu??o para v?rias demandas atuais dos sistemas computacionais: taxa de ociosidade das m?quinas, alto consumo de energia, ocupa??o de espa?o f?sico e dificuldade para gerenciamento de muitos sistemas operacionais em um mesmo datacenter. Entre as alternativas de virtualiza??o dispon?veis, o monitor de m?quina virtual Xen ? uma das op??es mais consolidadas e que possui melhor desempenho dentre as demais alternativas existentes. Para proporcionar sistemas virtualizados seguros, um aliado eficaz s?o os sistemas detectores de intrus?o que trabalham realizando monitora??o no tr?fego da rede. Este trabalho apresenta uma abordagem para detec??o de intrus?o em m?quinas virtuais baseadas no monitor de m?quina virtual Xen, introduzindo uma ferramenta para detectar e bloquear intrusos que estiverem tentando obter acesso indevido ao sistema. A ferramenta elaborada recebeu o nome de XenGuardian e trabalha realizando comunica??o entre as m?quinas virtuais (domU) com a m?quina h?spede (dom0). Na ocorr?ncia de tentativas de acesso n?o autorizadas, a m?quina h?spede realiza o tratamento da ocorr?ncia bloqueando o usu?rio. Para validar a solu??o, exploits foram utilizados, desferindo ataques contra sistemas de detec??o de intrusos e auferindo medi??es de desempenho atrav?s do benchmark NetPerf.
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Mahmud, Nesredin. "Automated Orchestra for Industrial Automation on Virtualized Multicore Environment." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-23672.
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Industrial control systems are applied in many areas e.g., motion control for industrial robotics, process control of large plants such as in the area of oil and gas, and in large national power grids. Since the last decade with advancement and adoption of virtualization and multicore technology (e.g., Virtual Monitoring Machine, cloud computing, server virtualization, application virtualization), IT systems, automation industries have benefited from low investment, effective system management and high service availability. However, virtualization and multicore technologies have posed a serious challenge to real-time systems, which is violating timeliness and predictability of real-time application running on control systems. To address the challenge, we have extended a real-time component-based framework with virtual nodes; and evaluated the framework in the context of virtualized multicore environment. The evaluation is demonstrated by modeling and implementing an orchestra application with QoS for CPU, memory and network bandwidth. The orchestra application is a real-time and distributed application deployed on virtualized multicore PCs connected with speakers. The result shows undistorted orchestra performance played through speakers connected to physical computer nodes. The contribution of the thesis can be considered: 1) extending a real-time component-based framework, Future Automation Software Architecture (FASA) with virtual nodes using Virtual Computation Resource (VCR) and 2) design and installation of reusable test environment for development, debugging and testing of real-time application on a network of virtualized multicore environment.<br>Vinnova project “AUTOSAR for Multi-Core in Automotive and Automation Industries “
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Silva, Cyrus Dias da. "Monitoramento e Cumprimento de Acordos de Nível de Serviço em Ambientes Virtualizados usando um Controlador de CPU." Universidade Federal de Pernambuco, 2013. https://repositorio.ufpe.br/handle/123456789/11621.
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Previous issue date: 2013-09-12<br>A virtualização de servidores tem trazido mudanças no mundo da hospedagem de sites e aplicações web. Na abordagem tradicional, por questões de isolamento cada máquina física fica atrelada a uma aplicação ou a um serviço, o que acarreta em uma subutilização dos recursos computacionais. A virtualização de servidores supera essa limitação proporcionando diversos benefícios como: a redução nos custos operacionais (dado que são necessárias menos máquinas físicas), utilização mais eficiente dos recursos e um menor tempo para disponibilização de servidores.
A utilização de acordos de nível de serviço (SLAs) é uma prática comum que ocorre na hospedagem de aplicações web. No entanto, existem desafios no cumprimento de SLAs em ambientes virtualizados. Um deles é que não é trivial converter os objetivos de nível de serviço (SLOs) que usam métricas de nível de aplicação, como tempo de resposta ou transações por segundo, na alocação de recursos de baixo nível, como CPU e memória. Além disso, visto que a carga de trabalho em que os servidores são submetidos varia com o tempo, alocações de recursos estáticas só são suficientes para garantir o nível de serviço se os recursos forem alocados para os picos de demanda, o que leva a subutilização no restante do tempo.
Nesta dissertação foi desenvolvida uma solução de monitoramento e controle que ajusta dinamicamente os parâmetros do escalonamento de CPU do ambiente virtualizado de forma a evitar que os acordos de nível de serviço sejam violados. A abordagem utilizada foi derivada de um controlador de referência na literatura. Foram realizados experimentos num ambiente com o hypervisor Xen usando uma aplicação e cargas representativas, e as soluções foram avaliadas. Os resultados obtidos foram compatíveis para os cenários investigados.
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Jing, Wei. "Performance Isolation for Mixed Criticality Real-time System on Multicore with Xen Hypervisor." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-193603.
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Multicore processors have imported the powerful computing capacity to real-time systems, allowing the multi-task execution on the co-running cores. Meanwhile, the competition for the shared resources among the on-die cores brings the side-effects which highly degrades the performance of single cores and puts the real-time requirements in danger. This thesis work is focused on addressing the memory access contentions on the real-time systems with mixed-criticality. A throttling algorithm is designed to control the memory access flows from the interfering side, securing the deadlines of critical tasks. We implemented the throttling framework on Xen Hypervisor and evaluated the overall isolating performance with a set of benchmarks. The results prove the effectiveness of our design.
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Sheinidashtegol, Pezhman. "Impact of DDoS Attack on the Three Common HypervisorS(Xen, KVM, Virtual Box)." TopSCHOLAR®, 2016. http://digitalcommons.wku.edu/theses/1646.
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Cloud computing is a technology of inter-connected servers and resources that use virtualization to utilize the resources, flexibility, and scalability. Cloud computing is accessible through the network. This accessibility and utilization have its own benefit and drawbacks. Utilization and scalability make this technology more economic and affordable for even small businesses. Flexibility drastically reduces the risk of starting businesses. Accessibility allows cloud customers not to be restricted in a specific location until they could have access to the network, and in most cases through the internet.
These significant traits, however, have their own disadvantages. Easy accessibility makes it more convenient for the malicious user to have access to servers in the cloud. Virtualizations that come to existence by middleware software called Virtual Machine Managers (VMMs) or hypervisors come with different vulnerabilities. These vulnerabilities are adding to previously existed vulnerability of Networks and Operating systems and Applications. In this research we are trying to distinguish the most resistant Hypervisor between (Xen, KVM and Virtual Box) against Distributed Denial of Service (DDoS) attack, an attempt to saturate victim’s resources making them unavailable to legitimate users, or shutting down the services by using more than one machine as attackers by targeting three different resources (Network, CPU, Memory). This research will show how hypervisors act differently under the same attacks and conditions.
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Bavelski, Alexei. "On the Performance of the Solaris Operating System under the Xen Security-enabled Hypervisor." Thesis, Linköping University, Department of Computer and Information Science, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-9148.
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<p>This thesis presents an evaluation of the Solaris version of the Xen virtual machine monitor and a comparison of its performance to the performance of Solaris Containers under similar conditions. Xen is a virtual machine monitor, based on the paravirtualization approach, which provides an instruction set different to the native machine environment and therefore requires modifications to the guest operating systems. Solaris Zones is an operating system-level virtualization technology that is part of the Solaris OS. Furthermore, we provide a basic performance evaluation of the security modules for Xen and Zones, known as sHype and Solaris Trusted Extensions, respectively.</p><p>We evaluate the control domain (know as Domain-0) and the user domain performance as the number of user domains increases. Testing Domain-0 with an increasing number of user domains allows us to evaluate how much overhead virtual operating systems impose in the idle state and how their number influences the overall system performance. Testing one user domain and increasing the number of idle domains allows us to evaluate how the number of domains influences operating system performance. Testing concurrently loaded increasing numbers of user domains we investigate total system efficiency and load balancing dependent on the number of running systems.</p><p>System performance was limited by CPU, memory, and hard drive characteristics. In the case of CPU-bound tests Xen exhibited performance close to the performance of Zones and to the native Solaris performance, loosing 2-3% due to the virtualization overhead. In case of memory-bound and hard drive-bound tests Xen showed 5 to 10 times worse performance.</p>
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Tippa, Nani. "Design of client aware scheduler for XEN with enhanced techniques to improve cloud performance." Thesis, Wichita State University, 2013. http://hdl.handle.net/10057/6842.
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Infrastructure as a Service (IaaS) in cloud provides ample scope for various high volume
applications to be run on the servers across the WAN, availing a fair service to the end clients.
Many effective schedulers have been designed to consider the contention of the computational
and communicational resources, which provide a guaranteed effectiveness for resource sharing.
However, the vast diversity of client devices in a cloud demand scheduling based on their
features and capabilities. Mobile clients, workstations, laptops, PDAs and thin clients in the
cloud vary in aspects such as processing power, screen size, battery life, geographical distance
and many. Algorithms in the cloud, which are based on client capabilities result in many
consumer benefits such as network load balancing, saving battery, reducing latency, efficient
processing. In this thesis, the authors propose a client aware credit scheduler for virtualized
server setup in a cloud that schedules the client requests based on the client device features and
capabilities. Rich Internet Applications (RIA) is proposed, in order for the server to realize the
client device capabilities such as the type of client, the battery remaining and the location of the
client. Results show that the client-aware credit scheduler is effective in terms of saving energy
and reducing response latency.<br>Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Electrical Engineering and Computer Science
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Pereira, Neto Miguel. "Uma an?lise do termo xen?s em O sofista e O pol?tico." Universidade Federal do Rio Grande do Norte, 2012. http://repositorio.ufrn.br:8080/jspui/handle/123456789/16510.
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Previous issue date: 2012-11-06<br>Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior<br>Neste trabalho abordaremos o h?spede como personagem e m?todo na obra plat?nica,
com destaque para os di?logos O Sofista e O Pol?tico de Plat?o, e como essa no??o de
h?spede conduz ao inqu?rito do que seria um sofista, um pol?tico e um fil?sofo.
Come?aremos com a teoriza??o dos poss?veis significados para estrangeiro aos quais
h?spede pode estar ligado ou n?o, mostrando como o problema da recep??o das diferen?as
pode ser pensado na obra plat?nica pelo prisma do estrangeiro. Analisaremos especificamente
o di?logo O Sofista, apresentando a proposta do di?logo enquanto uma busca pelas
diferen?as, tanto no ramo ontol?gico quanto na defini??o do sofista. Da mesma forma,
analisaremos o di?logo O Pol?tico, mostrando as rela??es que esse di?logo guarda com o seu
anterior (O Sofista), no sentido de continuar uma investiga??o e mostrar como o pol?tico deve
ser uma figura de concilia??o dos problemas. Apresentaremos uma proposta visando pensar o
?ltimo termo da investiga??o lan?ada em O Sofista: o Fil?sofo como uma proposta que Plat?o
demonstra atrav?s de rela??es durante toda a sua obra e n?o apenas num di?logo, concluindo
o trabalho com as rela??es que os textos nos deixaram para pensar o Fil?sofo a partir do
prisma da hospitalidade
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CUTOLO, CARLO ALBERTO. "XEN gel stent for the treatment of open-angle glaucoma: real-world effectiveness and safety." Doctoral thesis, Università degli studi di Genova, 2021. http://hdl.handle.net/11567/1045088.
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The term glaucoma refers to a broad group of diseases causing characteristic optic nerve damage. Elevated intraocular pressure (IOP) does not define glaucoma but has been strongly associated with the development and progression of glaucomatous damage and is currently the only modifiable risk factor. Among new surgical procedure to reduce IOP, the XEN gel stent implantation offers sub-conjunctival filtration by the implantation of a flexible 6mm tube. In the present work we have prospectively collected data on XEN implantations performed at our site with the aim to assess the efficacy and safety of the procedure. In this research we found that a post-operative IOP below or equal to 9 mmHg, which is the theoretical pressure drop of the implant, is also predictive of long-term efficacy of the procedure. We reported and analysed two relevant complications regarding the XEN implantation. Choroidal detachment has been associated with higher patient's age and with an increased number of IOP-lowering drugs. We also reported cases where the implant appeared damaged during the follow-up and we described the clinical course. Then, comparing XEN with trabeculectomy, we found that the two procedures are comparable when the IOP success criterion is in the mid-teens but is favourable to trabeculectomy when a very low IOP target is needed.
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Paca, Agnieszka Maria. "Differentiation of extraembryonic endoderm stem cell lines and parietal endoderm into visceral endoderm : the art of XEN cells." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/6227.
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The extraembryonic endoderm of mammals is essential for nutritive support of the foetus and patterning of the early embryo. Visceral and parietal endoderm are major subtypes of this lineage with the former exhibiting most, if not all, of the embryonic patterning properties. Extraembryonic endoderm (XEN) cell lines derived from the primitive endoderm of mouse blastocysts represent a cell culture model of this lineage, but are biased towards parietal endoderm in culture and in chimaeras. Here, I further characterise XEN cells and show that these cell lines exhibit high levels of heterogeneity. In an effort for XEN cells to adopt visceral endoderm character different aspects of the in vivo environment were mimicked. I found that BMP4 and laminin promote a mesenchymal-to-epithelial transition of XEN cells with upregulation of epithelial markers and downregulation of mesenchymal markers. Gene expression analysis showed the differentiated XEN cells most resembled extraembryonic visceral endoderm. Correspondingly, inhibition of Erk and BMP signalling drives XEN cells toward parietal endoderm fate. Finally, I show that BMP4 treatment of freshly isolated parietal endoderm from Reichert’s membrane promotes its visceral endoderm differentiation. This suggests that parietal endoderm is still developmentally plastic and can be transdifferentiated to a visceral endoderm in response to BMP. Generation of visceral endoderm from XEN cells uncovers the true potential of these blastocyst-derived cells and is a significant step towards modelling early developmental events ex vivo.
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Chiru, Cezar. "Resource based analysis of Ethernet communication between software partitions." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-27396.
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Nowadays, Industrial Control Systems (ICSs) are becoming larger and implement more complex functions. Therefore, technologies that are currently used to implement these functions, like hardware platforms and communication protocols might soon become unusable due to the lack of resources. The industry is trying to adopt new technologies that will allow these functionalities to be developed without an increase in the size of the equipment, or of the development costs. To enumerate some of these technologies: virtualization, multi-core technologies are the ones that show the biggest potential. Because these technologies are not mature, research has to be done in order to fully maximize their potential. Another technology that is highly used by the industry is the Ethernet communication protocol. It presents some advantages, but due to the non-real-time nature of the applications that it was designed for, it has to be extended in order to be used in real-time applications. The objective of this thesis work is to model an Ethernet network comprised of software partitions so that it can provide timing guarantees for the traffic that traverses the network. A Response Time Analysis for real-time flows over such networks is proposed. The model and the RTA are evaluated by experiments.
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Enkvist, Clas. "Integrerad modulär avionik med virtualisering." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-98433.
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Det finns huvudsakligen tre olika sätt att konstruera ett partitionerat system på: Federerad arkitektur, Integrerad Modulär Avionik (IMA) med ARINC 653 eller IMA med virtualisering. I den här rapporten undersöks de olika arkitekturernas egenskaper och vilka möjligheter som finns för certifiering av dem. Efter den teoretiska undersökningen har Virtualisering, och framförallt Xen, valts ut för en testimplementation och tillförlitlighetstester. Testimplementationen består av fyra partitioner där varje partition har sin specifika uppgift att lösa. Den fjärde partitionen används för att undersöka hur Xen hanterar en partition som aggressivt nyttjar I/O, processor eller arbetsminne. Testerna visar att Xen har en svag punkt: all I/O hanteras via en egen, speciell, partition. Denna partition saknar dessutom möjligheter att prioritera I/O från specifika partitioner. Den slutgiltiga slutsatsen av de tester som genomförts är att ett system byggt på Xen inte kan lämna samma tillförlitlighet som ett system med en federerad arkitektur eller ett system som bygger på ARINC 653.<br>One can basically take three different approaches when designing a partitioned avionic system: Federated Architecture, Integrated Modular Avionics (IMA) with ARINC 653 or IMA with Virtualization. This report examines the different architectural characteristics and the possibilities for certifying them. After the theoretical investigation, Virtualization and, in particular, Xen has been selected for a trial implementation and reliability tests. The implementation consists of four partitions where each partition has its own specific task to solve. The fourth partition is used to examine how Xen handles a partition that aggressively utilizes I/O, processor or memory resources. Tests show that Xen has a weak point: all I/O is handled through a separate and unique partition. This partition also lacks the ability of prioritizing I/O from specific partitions. The final conclusion of the tests carried out in this thesis is that a system built on Xen cannot provide the same reliability as a system with a federated architecture or a system based on ARINC 653.
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Bruschi, Gustavo Cesar [UNESP]. "StackAct: avaliação de desempenho em uma nuvem IaaS multicamadas." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/141446.
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Previous issue date: 2016-06-01<br>A Computação em Nuvem tornou-se sinônimo de qualidade e eficiência em investimento na área de Tecnologia de Informação, criando novos desafios para o processamento e integração de dados. O desempenho da solução adotada é um ponto chave para o sucesso de uma solução em Nuvem, assim como a maneira como as máquinas virtuais realizam a leitura e gravação no armazenamento, podem ser determinantes para uma melhor utilização desta solução. Este trabalho apresenta o StackAct, um mecanismo que permite realizar o monitoramento e obter dados, em uma Nuvem IaaS, relativos ao consumo de recursos computacionais de uma solução em três camadas utilizando orquestrador Apache CloudStack com hypervisor XenServer e armazenamento dos dados no sistema Openfiler. Foram realizados testes de desempenho utilizando três diferentes tipos de perfil de instâncias em uma nuvem computacional privada, possibilitando mensurar os consumos de CPU, E/S e Memória nas três camadas envolvidas, com diferentes tipos de ofertas de serviços. Os testes resultaram em um comparativo entre cada item analisado para cada camada individual, onde foi possível detectar uma pequena variação entre as diferentes configurações de testes devido a forma como a camada do hypervisor enfileira as requisições realizadas pela camada do orquestrador. Já no comparativo realizado entre as camadas, foi possível constatar o alto consumo de disco na camada de armazenamento de dados, em especial E/S de gravação de dados, que levaram a realização de outros testes utilizando disco de estado sólido na camada de armazenamento, tendo um grande impacto no desempenho da solução como um todo. Foi detectado também um alto consumo de memória na camada hypervisor, que é justificada pela alocação do próprio hypervisor além das VMs que estão sendo criadas e utilizadas no processo.<br>Cloud Computing has become synonymous of quality, efficiency, and return of investment in Information Technology, creating new challenges for processing and data integrations. The performance of the adopted solution is a key to the success of a solution on Cloud, as well as the way that virtual machines use reading and writing to storage, which can be decisive for a better use of this solution. This work presents the StackAct, a mechanism that allows for monitoring and obtaining data on the consumption of computing resources of a solution in three layers using orchestrator IaaS Apache CloudStack with XenServer hypervisor and storage of data on the NAS OpenFiler system. Based on this mechanism, performance tests were conducted using three different instances of a private cloud. CPU, I/O, and memory usages in the three layers involved were measured with different types of loads. The tests resulted in a comparison between each item analyzed for each individual layer, and it was possible to detect a slight variation between the different configurations of tests because of the way that the hypervisor layer queues the requests made by the orchestrator layer. In the comparison made between the layers, it was possible to high consumption of disk in the data storage layer, in particular I/O data recording, which led to other tests using solid state disk in the storage layer, having an high impact on the performance of the solution as a whole. It was also detected high memory in the hypervisor layer, which is justified by the allocation of the hypervisor itself beyond the VMs being created and used in the process.
36
Lu, Peng. "Resilire: Achieving High Availability Through Virtual Machine Live Migration." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/25434.
Full textAbstract:
High availability is a critical feature of data centers, cloud, and cluster computing environments. Replication is a classical approach to increase service availability by providing redundancy. However, traditional replication methods are increasingly unattractive for deployment due to several limitations such as application-level non-transparency, non-isolation of applications (causing security vulnerabilities), complex system management, and high cost. Virtualization overcomes these limitations through another layer of abstraction, and provides high availability through virtual machine (VM) live migration: a guest VM image running on a primary host is transparently check-pointed and migrated, usually at a high frequency, to a backup host, without pausing the VM; the VM is resumed from the latest checkpoint on the backup when a failure occurs. A virtual cluster (VC) generalizes the VM concept for distributed applications and systems: a VC is a set of multiple VMs deployed on different physical machines connected by a virtual network.
This dissertation presents a set of VM live migration techniques, their implementations in the Xen hypervisor and Linux operating system kernel, and experimental studies conducted using benchmarks (e.g., SPEC, NPB, Sysbench) and production applications (e.g., Apache webserver, SPECweb). We first present a technique for reducing VM migration downtimes called FGBI. FGBI reduces the dirty memory updates that must be migrated during each migration epoch by tracking memory at block granularity. Additionally, it determines memory blocks with identical content and shares them to reduce the increased memory overheads due to block-level tracking granularity, and uses a hybrid compression mechanism on the dirty blocks to reduce the migration traffic. We implement FGBI in the Xen hypervisor and conduct experimental studies, which reveal that the technique reduces the downtime by 77% and 45% over competitors including LLM and Remus, respectively, with a performance overhead of 13%.
We then present a lightweight, globally consistent checkpointing mechanism for virtual cluster, called VPC, which checkpoints the VC for immediate restoration after (one or more) VM failures. VPC predicts the checkpoint-caused page faults during each checkpointing interval, in order to implement a lightweight checkpointing approach for the entire VC. Additionally, it uses a globally consistent checkpointing algorithm, which preserves the global consistency of the VMs' execution and communication states, and only saves the updated memory pages during each checkpointing interval. Our Xen-based implementation and experimental studies reveal that VPC reduces the solo VM downtime by as much as 45% and reduces the entire VC downtime by as much as 50% over competitors including VNsnap, with a memory overhead of 9% and performance overhead of 16%.
The dissertation's third contribution is a VM resumption mechanism, called VMresume, which restores a VM from a (potentially large) checkpoint on slow-access storage in a fast and efficient way. VMresume predicts and preloads the memory pages that are most likely to be accessed after the VM's resumption, minimizing otherwise potential performance degradation due to cascading page faults that may occur on VM resumption. Our experimental studies reveal that VM resumption time is reduced by an average of 57% and VM's unusable time is reduced by 73.8% over native Xen's resumption mechanism.
Traditional VM live migration mechanisms are based on hypervisors. However, hypervisors are increasingly becoming the source of several major security attacks and flaws. We present a mechanism called HSG-LM that does not involve the hypervisor during live migration. HSG-LM is implemented in the guest OS kernel so that the hypervisor is completely bypassed throughout the entire migration process. The mechanism exploits a hybrid strategy that reaps the benefits of both pre-copy and post-copy migration mechanisms, and uses a speculation mechanism that improves the efficiency of handling post-copy page faults. We modify the Linux kernel and develop a new page fault handler inside the guest OS to implement HSG-LM. Our experimental studies reveal that the technique reduces the downtime by as much as 55%, and reduces the total migration time by as much as 27% over competitors including Xen-based pre-copy, post-copy, and self-migration mechanisms.
In a virtual cluster environment, one of the main challenges is to ensure equal utilization of all the available resources while avoiding overloading a subset of machines. We propose an efficient load balancing strategy using VM live migration, called DCbalance. Differently from previous work, DCbalance records the history of mappings to inform future placement decisions, and uses a workload-adaptive live migration algorithm to minimize VM downtime. We improve Xen's original live migration mechanism and implement the DCbalance technique, and conduct experimental studies. Our results reveal that DCbalance reduces the decision generating time by 79%, the downtime by 73%, and the total migration time by 38%, over competitors including the OSVD virtual machine load balancing mechanism and the DLB (Xen-based) dynamic load balancing algorithm.
The dissertation's final contribution is a technique for VM live migration in Wide Area Networks (WANs), called FDM. In contrast to live migration in Local Area Networks (LANs), VM migration in WANs involve migrating disk data, besides memory state, because the source and the target machines do not share the same disk service. FDM is a fast and storage-adaptive migration mechanism that transmits both memory state and disk data with short downtime and total migration time. FDM uses page cache to identify data that is duplicated between memory and disk, so as to avoid transmitting the same data unnecessarily. We implement FDM in Xen, targeting different disk formats including raw and Qcow2. Our experimental studies reveal that FDM reduces the downtime by as much as 87%, and reduces the total migration time by as much as 58% over competitors including pre-copy or post-copy disk migration mechanisms and the disk migration mechanism implemented in BlobSeer, a widely used large-scale distributed storage service.<br>Ph. D.
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Rocha, Marcelo Matos. "Efeito do uso combinado de bisfosfonato e enxerto xen?geno na repara??o ?ssea alveolar : estudo histomorfom?trico." Pontif?cia Universidade Cat?lica do Rio Grande do Sul, 2018. http://tede2.pucrs.br/tede2/handle/tede/7906.
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Previous issue date: 2018-01-12<br>Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES<br>Bisphosphonates have been associated with medication-related osteonecrosis of the jaw
(MRONJ), a disorder that has some risk factors such as surgical interventions in the jaw
bones, especially tooth extractions. On the other hand, xenogeneic grafts have been widely
used to fill the alveolar socket after tooth extraction, with clinical evidences of improving
local conditions of the surgical bed for oral rehabilitation. The aim of this study was to
investigate the effect of combined bisphosphonate and the xenogeneic graft Bio-Oss?
Collagen on alveolar bone repair after tooth extraction. Sixty rats were allocated into five
groups according to the treatment received: zoledronic acid (group 1) and alendronate
(group 2) both with xenogeneic graft; zoledronic acid (group 3) and alendronate (group 4)
both without xenogeneic graft; and control (group 5). All animals were subjected to tooth
extractions, and maxillae were dissected and macro- and microscopically analyzed.
Frequency of oral mucosal wounds did not significantly differ between the groups;
however, these lesions were significantly smaller in the control group. The amount of
fibrous connective tissue was greater in groups 2 (alendronate/Bio-Oss) and 5 (control)
than in 3 (zoledronic acid) and 4 (alendronate). Group 4 showed greater amounts of vital
bone than did groups 1 (zoledronic acid/Bio-Oss), 3 and 5. The amounts of non-vital bone
were greater in the zoledronic acid groups (1 and 3), where non-vital bone was less in
group 1 than 3. Group 3 showed more inflammatory infiltrate than groups 2, 4 and 5. There
were greater amounts of microbial colonies in group 3. Inflammatory infiltrate and
microbial colonies were negatively correlated to vital bone and positively correlated to
non-vital bone. Inflammatory infiltrate and microbial colonies were positively correlated to
each other.
Conclusion: Post-extraction socket filling with Bio-Oss? Collagen did not prevent the
occurrence of non-vital bone and infection, but it did lower the extent of these variables in
rats under treatment with zoledronic acid.<br>Os bisfosfonatos t?m sido associados ? ocorr?ncia de osteonecrose maxilar (MRONJ,
medication-related osteonecrosis of the jaw), condi??o que tem, entre os fatores de risco
para sua ocorr?ncia, as interven??es cir?rgicas dos ossos maxilares, principalmente as
exodontias. Por outro lado, o uso de xenoenxerto para preenchimento alveolar ap?s
exodontia tornou-se procedimento frequente, com evid?ncias cl?nicas de sua capacidade
em melhorar as condi??es locais do s?tio cir?rgico com vistas ? reabilita??o oral. O
presente estudo teve por objetivo investigar o efeito do uso combinado de bisfosfonato e
enxerto xen?geno (Bio-Oss?Collagen) no reparo ?sseo alveolar ap?s exodontia. Sessenta
ratos foram distribu?dos em cinco grupos de acordo com o tratamento recebido: ?cido
zoledr?nico (grupo 1) e alendronato (grupo 2), ambos com xenoenxerto; ?cido zoledr?nico
(grupo 3) e alendronato (grupo 4), ambos sem xenoenxerto; e grupo-controle (grupo 5).
Todos os animais foram submetidos a exodontias, as maxilas foram dissecadas e analisadas
por meio de exame macro- e microsc?pico. A frequ?ncia de les?o da mucosa oral n?o
diferiu significativamente entre os grupos; entretanto essas les?es foram significativamente
menores no grupo-controle. A preval?ncia de tecido conjuntivo fibroso foi maior nos
grupos 2 (alendronato/Bio-Oss) e 5 (controle) do que nos grupos 3 (?cido zoledr?nico) e 4
(alendronato). O grupo 4 (alendronato) teve maior quantidade de osso vital do que os
grupos 1 (?cido zoledr?nico/Bio-Oss), 3 (?cido zoledr?nico) e controle. A quantidade de
osso n?o-vital foi maior nos grupos ?cido zoledr?nico com e sem Bio-Oss (1 and 3), sendo
que, ao comparar-se esses dois grupos entre si, essa vari?vel foi maior no grupo 3. O grupo
3 exibiu mais infiltrado inflamat?rio do que os grupos 2, 4 e 5 e maior quantidade de
col?nias microbianas do que os demais grupos. Infiltrado inflamat?rio e col?nias
microbianas tiveram correla??o negativa com osso vital e positiva com osso n?o-vital.
Infiltrado inflamat?rio e col?nias microbianas exibiram correla??o positiva entre si.
Conclus?o: O preenchimento do alv?olo p?s-exodontia com Bio-Oss? Collagen n?o evitou
a ocorr?ncia de osso n?o-vital e infec??o, mas foi capaz de diminuir a intensidade dessas
vari?veis nos ratos sob tratamento com ?cido zoledr?nico.
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CAMPEGIANI, PAOLO. "Resources allocation for virtualized architectures." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2009. http://hdl.handle.net/2108/1014.
Full textAbstract:
Viene proposto un modello formale per l'allocazione di risorse in un sistema multi-tier. I nodi di computazione sono implementati tramite delle macchine virtuali. Il modello gestisce risorse quantitative e qualitative e consente più livelli di servizio.
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Debeb, Bisrat Godefay. "Molecular characterization of oct4-expressing yolk sac endoderm stem cell lines." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2657.
Full text
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Lee, Min. "Memory region: a system abstraction for managing the complex memory structures of multicore platforms." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50398.
Full textAbstract:
The performance of modern many-core systems depends on the effective use of their complex cache and memory structures, and this will likely become more pronounced with the impending arrival of on-chip 3D stacked and non-volatile off-chip byte-addressable memory. Yet to date, operating systems have not treated memory as a first class schedulable resource, embracing memory heterogeneity. This dissertation presents a new software abstraction, called ‘memory region’, which denotes the current set of physical memory pages actively used by workloads. Using this abstraction, memory resources can be scheduled for applications to fully exploit a platform's underlying cache and memory system, thereby gaining improved performance and predictability in execution, particularly for the consolidated workloads seen in virtualized and cloud computing infrastructures. The abstraction's implementation in the Xen hypervisor involves the run-time detection of memory regions, the scheduled mapping of these regions to caches to match performance goals, and maintaining region-to-cache mappings using per-cache page tables. This dissertation makes the following specific contributions. First, its region scheduling method proposes that the location of memory blocks rather than CPU utilization is the principal determinant where workloads are run. It proposes a new scheduling method, the region scheduling that the location of memory blocks determines where the workloads are run. Second, treating memory blocks as first-class resources, new methods for efficient cache management are shown to improve application performance as well as the performance of certain operating system functions. Third, explicit memory scheduling makes it possible to disaggregate operating systems, without the need to change OS sources and with only small markups of target guest OS functionality. With this method, OS functions can be mapped to specific desired platform components, such as file system confined to running on specific cores and using only certain memory resources designated for its use. This can improve performance for applications heavily dependent on certain OS functions, by dynamically providing those functions with the resources needed for their current use, and it can prevent performance-critical application functionality from being needlessly perturbed by OS functions used for other purposes or by other jobs. Fourth, extensions of region scheduling can also help applications deal with the heterogeneous memory resources present in future systems, including on-chip stacked DRAM and NUMA or even NVRAM memory modules. More generally, regions scheduling is shown to apply to memory structures with well-defined differences in memory access latencies.
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Javaid, Salman. "Analysis and Detection of Heap-based Malwares Using Introspection in a Virtualized Environment." ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/td/1875.
Full textAbstract:
Malware detection and analysis is a major part of computer security. There is an arm race between security experts and malware developers to develop various techniques to secure computer systems and to find ways to circumvent these security methods. In recent years process heap-based attacks have increased significantly. These attacks exploit the system under attack via the heap, typically by using a heap spraying attack. The main drawback with existing techniques is that they either consume too many resources or are complicated to implement. Our work in this thesis focuses on new methods which offloads process heap analysis for guest Virtual Machines (VM) to the privileged domain using Virtual Machine Introspection (VMI) in a Cloud environment. VMI provides us with a seamless, non-intrusive and invisible (to malwares) way of observing the memory and state of VMs without raising red flags for the malwares.
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Nikolaev, Ruslan. "Design and Implementation of the VirtuOS Operating System." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/24964.
Full textAbstract:
Most operating systems provide protection and isolation to user processes, but not to critical system components such as device drivers or other systems code. Consequently, failures in these components often lead to system failures. VirtuOS is an operating system that exploits a new method of decomposition to protect against such failures. VirtuOS exploits virtualization to isolate and protect vertical slices of existing OS kernels in separate service domains. Each service domain represents a partition of an existing kernel, which implements a subset of that kernel's functionality. Service domains directly service system calls from user processes. VirtuOS exploits an exceptionless model, avoiding the cost of a system call trap in many cases. We illustrate how to apply exceptionless system calls across virtualized domains.
To demonstrate the viability of VirtuOS's approach, we implemented a prototype based on the Linux kernel and Xen hypervisor. We created and evaluated a network and a storage service domain. Our prototype retains compatibility with existing applications, can survive the failure of individual service domains while outperforming alternative approaches such as isolated driver domains and even exceeding the performance of native Linux for some multithreaded workloads.
The evaluation of VirtuOS revealed costs due to decomposition, memory management, and communication, which necessitated a fine-grained analysis to understand their impact on the system's performance. The interaction of virtual machines with multiple underlying software and hardware layers in virtualized environment makes this task difficult. Moreover, performance analysis tools commonly used in native environments were not available in virtualized environments. Our work addresses this problem to enable an in-depth performance analysis of VirtuOS. Our Perfctr-Xen framework provides capabilities for per-thread analysis with both accumulative event counts and interrupt-driven event sampling. Perfctr-Xen is a flexible and generic tool, supports different modes of virtualization, and can be used for many applications outside of VirtuOS.<br>Ph. D.
43
Krempa, Peter. "Analysis of Entropy Levels in the Entropy Pool of Random Number Generator." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2013. http://www.nusl.cz/ntk/nusl-236179.
Full textAbstract:
V informatice je pojem entropie obvykle znám jako nahodný proud dat. Tato práce krátce shrnuje metody generovaní nahodných dat a popisuje generátor náhodnych čísel, jež je obsažen v jádře operačního systému Linux. Dále se práce zabývá určením bitové rychlosti generování nahodných dat tímto generátorem ve virtualizovaném prosředí, které poskytují různé hypervizory. Práce popíše problémy nízkého výkonu generátory nahodných dat ve virtualním prostředí a navrhne postup pro jejich řešení. Poté je nastíňena implementace navržených postupů, které je podrobena testům a její vysledky jsou porovnány s původním systémem. Systém pro distribuci entropie může dále vylepšit množství entropie v sytémovém jádře o několik řádu, pokud je připojen k vykonému generátoru nahodných dat.
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Lindberg, Magnus. "Virtualisering : en prestandajämförelse mellan fullständig- och parallell systemvirtualisering." Thesis, University of Skövde, School of Humanities and Informatics, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-1159.
Full textAbstract:
<p>Virtualisering är en abstraktion av underliggande fysisk hårdvara som omvandlas till en förutbestämd struktur av hårdvara via mjukvara. En virtuell maskin kan då vara frånkopplad från hårdvaran. Virtualisering tillåter hårdvara att delas upp som flera separata virtuella hårdvaror vilket kan ske transparent för operativsystem i virtuella maskiner. Virtualisering ökade under 90-talet och det utvecklades två virtualiseringsteknologier: (i) den fullständiga systemvirtualisering och (ii) parallell systemvirtualisering. Fullständig systemvirtualisering erbjuder abstraktion som utgör en frånkoppling från hårdvara. Operativsystem som använder en virtuell maskin känner då inte till att virtualisering skett med resultatet att alla operativsystem kan användas. Parallell systemvirtualisering använder en delvis abstraktion då operativsystem modifieras för att virtuell maskin skall vara medveten om att virtualisering utförts för att möjliggöra för prestandaförbättringar. Den problemställningen som ställts försöker utröna vilken av dessa två teknologier som kan leverera bästa prestanda över FTP. Experiment har då utförts och visade att det är inga skillnader mellan teknologierna.</p>
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Mauricio, Leopoldo Alexandre Freitas. "Avaliação de desempenho de plataformas de virtualização de redes." Universidade do Estado do Rio de Janeiro, 2013. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=8138.
Full textAbstract:
O objetivo desta dissertação é avaliar o desempenho de ambientes virtuais de
roteamento construídos sobre máquinas x86 e dispositivos de rede existentes na Internet atual.
Entre as plataformas de virtualização mais utilizadas, deseja-se identificar quem melhor
atende aos requisitos de um ambiente virtual de roteamento para permitir a programação do
núcleo de redes de produção. As plataformas de virtualização Xen e KVM foram instaladas
em servidores x86 modernos de grande capacidade, e comparadas quanto a eficiência,
flexibilidade e capacidade de isolamento entre as redes, que são os requisitos para o bom
desempenho de uma rede virtual. Os resultados obtidos nos testes mostram que, apesar de ser
uma plataforma de virtualização completa, o KVM possui desempenho melhor que o do Xen
no encaminhamento e roteamento de pacotes, quando o VIRTIO é utilizado. Além disso,
apenas o Xen apresentou problemas de isolamento entre redes virtuais. Também avaliamos o
efeito da arquitetura NUMA, muito comum em servidores x86 modernos, sobre o desempenho
das VMs quando muita memória e núcleos de processamento são alocados nelas. A análise
dos resultados mostra que o desempenho das operações de Entrada e Saída (E/S) de rede pode
ser comprometido, caso as quantidades de memória e CPU virtuais alocadas para a VM não
respeitem o tamanho dos nós NUMA existentes no hardware. Por último, estudamos o
OpenFlow. Ele permite que redes sejam segmentadas em roteadores, comutadores e em
máquinas x86 para que ambientes virtuais de roteamento com lógicas de encaminhamento
diferentes possam ser criados. Verificamos que ao ser instalado com o Xen e com o KVM, ele
possibilita a migração de redes virtuais entre diferentes nós físicos, sem que ocorram
interrupções nos fluxos de dados, além de permitir que o desempenho do encaminhamento de
pacotes nas redes virtuais criadas seja aumentado. Assim, foi possível programar o núcleo da
rede para implementar alternativas ao protocolo IP.<br>The aim of this work is to evaluate the performance of routing virtual environments
built on x86 machines and network devices existing on the Internet today. Among the most
widely used virtualization platforms, we want to identify which best meets the requirements
of a virtual routing to allow programming of the core production networks. Virtualization
platforms Xen and KVM were installed on modern large capacity x86 machines, and they
were compared for efficiency, flexibility and isolation between networks, which are the
requirements for good performance of a virtual network. The tests results show that, despite
being a full virtualization platform, KVM has better performance than Xen in forwarding and
routing packets when the VIRTIO is used. Furthermore, only Xen had isolation problems
between networks. We also evaluate the effect of the NUMA architecture, very common in
modern x86 servers, on the performance of VMs when lots of memory and processor cores
are allocated to them. The results show that Input and Output (I/O) network performance can
be compromised whether the amounts of virtual memory and CPU allocated to VM do not
respect the size of the existing hardware NUMA nodes. Finally, we study the OpenFlow. It
allows slicing networks into routers, switches and x86 machines to create virtual
environments with different routing forwarding rules. We found that, when installed with Xen
and KVM, it enables the migration of virtual networks among different physical nodes,
without interruptions in the data streams, and allows to increase the performance of packet
forwarding in the virtual networks created. Thus, it was possible to program the core network
to implement alternatives to IP protocol.
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Shah, Tawfiq M. "Radium: Secure Policy Engine in Hypervisor." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc804971/.
Full textAbstract:
The basis of today’s security systems is the trust and confidence that the system will behave as expected and are in a known good trusted state. The trust is built from hardware and software elements that generates a chain of trust that originates from a trusted known entity. Leveraging hardware, software and a mandatory access control policy technology is needed to create a trusted measurement environment. Employing a control layer (hypervisor or microkernel) with the ability to enforce a fine grained access control policy with hyper call granularity across multiple guest virtual domains can ensure that any malicious environment to be contained. In my research, I propose the use of radium's Asynchronous Root of Trust Measurement (ARTM) capability incorporated with a secure mandatory access control policy engine that would mitigate the limitations of the current hardware TPM solutions. By employing ARTM we can leverage asynchronous use of boot, launch, and use with the hypervisor proving its state and the integrity of the secure policy. My solution is using Radium (Race free on demand integrity architecture) architecture that will allow a more detailed measurement of applications at run time with greater semantic knowledge of the measured environments. Radium incorporation of a secure access control policy engine will give it the ability to limit or empower a virtual domain system. It can also enable the creation of a service oriented model of guest virtual domains that have the ability to perform certain operations such as introspecting other virtual domain systems to determine the integrity or system state and report it to a remote entity.
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Oxenham, Michelle L. "Processes of transformation : art into pop and back again." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/78374/1/Michelle_Oxenham_Thesis.pdf.
Full textAbstract:
This research project was a case study for managing and innovating an interdisciplinary practice: specifically across music, performance and contemporary art. Key works included painting/sound/video installation, experimental performance, electronic pop music, music video and electronic pop music performance. An idiosyncratic and transformative use of colour emerged as an underlying theme and strategy for cohesion. The project offers strategies for the challenges of interdisciplinary practice specifically addressing the limitations related to institutionalised value systems, aesthetic traditions and disciplinary languages.
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Rabia, Tarek. "Virtualisation des fonctions d'un Cloud Radio Access Network(C-RAN)." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS009/document.
Full textAbstract:
La nouvelle génération de réseaux mobiles (5G) devrait faire face, durant les cinq prochaines années, à une importante croissance du volume de données, échangé entre plusieurs milliards d'objets et d'applications connectés. En outre, l'émergence de nouvelles technologies, telles que Internet of Things (IoT), conduite autonome et réalité augmentée, impose de plus fortes contraintes de performance et de qualité de service (QoS). Répondre aux besoins cités, tout en réduisant les dépenses d'investissement et d'exploitation (CAPEX/OPEX), sont les objectifs poursuivis par les opérateurs télécom, qui ont défini une nouvelle architecture d'accès radio, appelée Cloud Radio Access Network (C-RAN). Le principe du C-RAN est de centraliser, au sein d'un pool, les parties de traitement, BaseBand Unit (BBU), d'un RAN traditionnel. Les BBU sont alors dissociées de la station de base et de la partie radio, Remote Radio Unit (RRU). Ces deux parties restent néanmoins connectées à travers un réseau intermédiaire appelé Fronthaul (FH). Dans cette thèse, nous allons concevoir une nouvelle architecture C-RAN partiellement centralisée qui intègrera une plateforme de virtualisation basée sur un environnement Xen, nommée " Metamorphic Network " (MNet). A travers cette architecture, nous viserons à : i) mettre en place un pool, dans lequel des ressources physiques (processeurs, mémoire, ports réseaux, etc.) seront partagées entre des BBU virtualisées et d'autres applications, ii) établir un réseau FH ouvert aux fournisseurs de services et aux tierces parties, facilitant ainsi le déploiement des services au plus près des utilisateurs, pour une meilleure qualité d'expérience, iii) exploiter, à travers le FH, les infrastructures Ethernet existantes pour réduire les CAPEX/OPEX et enfin, iv) atteindre les performances réseau préconisées pour la 5G. Dans la première contribution, nous allons définir une nouvelle architecture Xen pour la plateforme MNet, intégrant le framework de packet processing, OpenDataPlane (ODP), au sein d’un domaine Xen privilégié, nommé « Driver Domain ». Notre objectif, à travers cette architecture, est d’accélérer le traitement des paquets de données transitant par MNet, en évitant la surutilisation, par ODP, des cœurs du processeur physique (CPU) de la plateforme. Pour cela, des cœurs CPU virtuels (vCPU) seront alloués dans le Driver Domain pour être exploités durant le traitement des paquets par ODP. Cette nouvelle plateforme MNet servira de base pour notre architecture C-RAN. Dans la seconde contribution, nous allons implémenter, au sein du FH, deux solutions réseau. La première solution, consistera à déployer le réseau de couche 2, Transparent Interconnection of Lots of Links (TRILL), pour connecter les différents éléments de notre architecture C-RAN. La seconde solution, consistera à déployer un réseau Software Defined Network (SDN), géré par le contrôleur distribué ONOS, qui sera virtualisé dans le pool BBU. Une comparaison des performances réseau sera réalisée entre ces deux solutions<br>Over the next five years, the new generation of mobile networks (5G) would face a significant growth of the data volume, exchanged between billions of connected objects and applications. Furthermore, the emergence of new technologies, such as Internet of Things (IoT), autonomous driving and augmented reality, imposes higher performance and quality of service (QoS) requirements. Meeting these requirements, while reducing the Capital and Operation Expenditures (CAPEX/OPEX), are the pursued goals of the mobile operators. Consequently, Telcos define a new radio access architecture, called Cloud Radio Access Network (C-RAN). The C-RAN principle is to centralize, within a pool, the processing unit of a radio interface, named BaseBand Unit (BBU). These two units are interconnected through a Fronthaul (FH) network. In this thesis, we design a new partially centralized C-RAN architecture that integrates a virtualization platform, based on a Xen environment, called Metamorphic Network (MNet). Through this architecture, we aim to: i) implement a pool in which physical resources (processors, memory, network ports, etc.) are shared between virtualized BBUs and other applications; ii) establish an open FH network that can be used by multiple operators, service providers and third parties to deploy their services and Apps closer to the users for a better Quality of Experience (QoE); iii) exploit, through the FH, the existing Ethernet infrastructures to reduce CAPEX/OPEX; and finally iv) provide the recommended network performance for the 5G. In the first contribution, we define a new Xen architecture for the MNet platform integrating the packet-processing framework, OpenDataPlane (ODP), within a privileged Xen domain, called Driver Domain (DD). This new architecture accelerates the data packet processing within MNet, while avoiding the physical CPUs overuse by ODP. Thus, virtual CPU cores (vCPU) are allocated within DD and are used by ODP to accelerate the packet processing. This new Xen architecture improves the MNet platform by 15%. In the second contribution, we implement two network solutions within the FH. The first solution consist of deploying a layer 2 network protocol, Transparent Interconnection of Lots of Links (TRILL), to connect multiple elements of our C-RAN architecture. The second solution consists of implementing a Software Defined Network (SDN) model managed by Open Network Operating System (ONOS), a distributed SDN controller that is which is virtualized within BBU pool. Moreover, a network performance comparison is performed between these two solutions
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Mohammad, Taha, and Chandra Sekhar Eati. "A Performance Study of VM Live Migration over the WAN." Thesis, Blekinge Tekniska Högskola, Institutionen för kommunikationssystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-1529.
Full textAbstract:
Virtualization is the key technology that has provided the Cloud computing platforms a new way for small and large enterprises to host their applications by renting the available resources. Live VM migration allows a Virtual Machine to be transferred form one host to another while the Virtual Machine is active and running. The main challenge in Live migration over WAN is maintaining the network connectivity during and after the migration. We have carried out live VM migration over the WAN migrating different sizes of VM memory states and presented our solutions based on Open vSwitch/VXLAN and Cisco GRE approaches. VXLAN provides the mobility support needed to maintain the network connectivity between the client and the Virtual machine. We have setup an experimental testbed to calculate the concerned performance metrics and analyzed the performance of live migration in VXLAN and GRE network. Our experimental results present that the network connectivity was maintained throughout the migration process with negligible signaling overhead and minimal downtime. The downtime variation experience with change in the applied network delay was relatively higher when compared to variation experienced when migrating different VM memory states. The total migration time experienced showed a strong relationship with size of the migrating VM memory state.<br>0763472814
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Rego, Paulo Antonio Leal. "FairCPU: Uma Arquitetura para Provisionamento de MÃquinas Virtuais Utilizando CaracterÃsticas de Processamento." Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=7653.
Full textAbstract:
FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico<br>O escalonamento de recursos à um processo chave para a plataforma de ComputaÃÃo em Nuvem, que geralmente utiliza mÃquinas virtuais (MVs) como unidades de escalonamento. O uso de tÃcnicas de virtualizaÃÃo fornece grande flexibilidade com a habilidade de instanciar vÃrias MVs em uma mesma mÃquina fÃsica (MF), modificar a capacidade das MVs e migrÃ-las entre as MFs. As tÃcnicas de consolidaÃÃo e alocaÃÃo dinÃmica de MVs tÃm tratado o impacto da sua utilizaÃÃo como uma medida independente de localizaÃÃo. à geralmente aceito que o desempenho de uma MV serà o mesmo, independentemente da MF em que ela à alocada. Esta à uma suposiÃÃo razoÃvel para um ambiente homogÃneo, onde as MFs sÃo idÃnticas e as MVs estÃo executando o mesmo sistema operacional e aplicativos. No entanto, em um ambiente de ComputaÃÃo em Nuvem, espera-se compartilhar um conjunto composto por recursos heterogÃneos, onde as MFs podem variar em termos de capacidades de seus recursos e afinidades de dados. O objetivo principal deste trabalho à apresentar uma arquitetura que possibilite a padronizaÃÃo da representaÃÃo do poder de processamento das MFs e MVs, em funÃÃo de Unidades de Processamento (UPs), apoiando-se na limitaÃÃo do uso da CPU para prover isolamento de desempenho e manter a capacidade de processamento das MVs independente da MF subjacente. Este trabalho busca suprir a necessidade de uma soluÃÃo que considere a heterogeneidade das MFs presentes na infraestrutura da Nuvem e apresenta polÃticas de escalonamento baseadas na utilizaÃÃo das UPs. A arquitetura proposta, chamada FairCPU, foi implementada para trabalhar com os hipervisores KVM e Xen, e foi incorporada a uma nuvem privada, construÃda com o middleware OpenNebula, onde diversos experimentos foram realizados para avaliar a soluÃÃo proposta. Os resultados comprovam a eficiÃncia da arquitetura FairCPU em utilizar as UPs para reduzir a variabilidade no desempenho das MVs, bem como para prover uma nova maneira de representar e gerenciar o poder de processamento das MVs e MFs da infraestrutura.<br>Resource scheduling is a key process for cloud computing platform, which generally
uses virtual machines (VMs) as scheduling units. The use of virtualization techniques
provides great flexibility with the ability to instantiate multiple VMs on one physical machine
(PM), migrate them between the PMs and dynamically scale VMâs resources. The techniques
of consolidation and dynamic allocation of VMs have addressed the impact of its use as an
independent measure of location. It is generally accepted that the performance of a VM will be
the same regardless of which PM it is allocated. This assumption is reasonable for a homogeneous
environment where the PMs are identical and the VMs are running the same operating
system and applications. Nevertheless, in a cloud computing environment, we expect that a set
of heterogeneous resources will be shared, where PMs will face changes both in terms of their
resource capacities and as also in data affinities. The main objective of this work is to propose
an architecture to standardize the representation of the processing power by using processing
units (PUs). Adding to that, the limitation of CPU usage is used to provide performance isolation
and maintain the VMâs processing power at the same level regardless the underlying PM.
The proposed solution considers the PMs heterogeneity present in the cloud infrastructure and
provides scheduling policies based on PUs. The proposed architecture is called FairCPU and
was implemented to work with KVM and Xen hypervisors. As study case, it was incorporated
into a private cloud, built with the middleware OpenNebula, where several experiments were
conducted. The results prove the efficiency of FairCPU architecture to use PUs to reduce VMsâ
performance variability, as well as to provide a new way to represent and manage the processing
power of the infrastructureâs physical and virtual machines.