19 novembre 2012

Paper: Best Practices for Oversubscription of CPU, Memory and Storage in vSphere Virtual Environments

VKernel, now part of DELL has released a paper titled:"Best Practices for Oversubscription of CPU, Memory and Storage in vSphere Virtual Environments". The paper which can be downloaded after registration contains 13 pages and is written by Scott D. Lowe and provides insight in the pros and cons of oversubscription of Processing, Memory and Storage resources. Scott also details how far oversubscription should be taken before it becomes dangerous. Scott uses vOps Server Explorer, for which VKernel recently released version 6 as the... [Lire la suite]
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21 juin 2011

VMware vFabric 5 optimise la gestion des ressources mémoire

VMware vFabric 5 propose un nouveau modèle de licence (par machine virtuelle) et une optimisation dynamique de la mémoire utilisée par les applications Java. VMware vient d’annoncer la sortie de vFabric 5, sa plate-forme applicative dédiée aux environnements virtuels et au monde du cloud computing. Au centre de cette offre se trouve le framework Java Spring, aujourd’hui passé dans le giron de VMware. L’ensemble est spécifiquement optimisé pour vSphere. Au menu de cette nouvelle version, tc Server (un serveur d’applications Java basé... [Lire la suite]
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04 mai 2011

Understanding Memory Compression in vSphere 4.1

vSphere 4.1 comes with a new performance-enhancing feature called memory compression. It can give your system a performance boost when it starts running low on RAM. Just like swap memory, memory compression is not equal to real memory but can help to prevent degradation of performance when you're running low on memory. For comparison, memory compression is faster than swap on disk but slower than real memory. --> The rest of the article and explanation is on the blog : http://www.petri.co.il/memory-compression-in-vsphere-4-1.htm
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03 septembre 2010

Guest Paging vs. Virtualization Paging and Negative Memory Availability

Jeff has discussed this at some length over on the virtualization team blog, but as a general rule of thumb we believe that it is much better to have paging occur inside the guest operating system rather than at the virtualization layer (if paging is needed). The simple reason for this is that the guest operating system has far better understanding of which are the best sections of memory to page out – where as all the virtualization layer can do is to guess at what should be paged out. In my recent demonstrations of dynamic... [Lire la suite]
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14 avril 2010

Dynamic Memory Coming to Hyper-V Part 3…

Memory Overcommit, an Overloaded Term… When it comes to virtualization and memory, I regularly hear the term “memory overcommit” used as if it’s a single technology. The problem is that there are numerous techniques that can be employed to more efficiently use memory which has led to much confusion. Some customers think page sharing equals overcommit. Others think second level paging equals memory overcommit and so on. So, to avoid any confusion, here’s the definition of overcommit according to the Merriam Webster dictionary... [Lire la suite]
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30 mars 2010

Dynamic Memory Coming to Hyper-V Part 2…

====================================================== Preamble: The point of this series, and the spirit in which it is written, is to take a holistic approach at the issues facing our customers, discuss the complexities with regard to memory management and explain why we’re taking the approach we are with Hyper-V Dynamic Memory. This isn’t meant to criticize anyone or technology, rather to have an open and transparent discussion about the problem space. ====================================================== ... [Lire la suite]
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18 mars 2010

Dynamic Memory Coming To Hyper-V

Virtualization Nation, I’ve had the pleasure of talking with customers in the last few months and the Hyper-V R2 reception has been nothing but unequivocally positive. Whether it’s been folks in small, medium or the enterprise, they appreciate the new capabilities in Windows Server 2008 R2 Hyper-V and the free Microsoft Hyper-V Server 2008 R2. At the same time, we’re always listening to our customers to better understand their business requirements and requests so we know know what to build for subsequent releases. Today, we’re... [Lire la suite]
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11 mars 2010

Reclaiming idle memory

In the “CPU/MEM Reservation Behavior” article there was a lively discussion going on between Chris Huss(vmtrainers.com) and myself. I think the following comment by Chris more or less summarizes the discussionI wasn’t aware that the balloon driver was involved with the Mem.IdleTax. I haven’t seen any documentation stating this…and assumed that the VMkernel just stopped mapping idle memory for the VM without letting it know. If the VM needed the memory again, the VMkernel would just re-map it. I can be totally wrong about this, but... [Lire la suite]
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14 septembre 2009

Memory alarms triggered with AMD RVI and Intel EPT?

I’ve reported on this twice already but it seems a fix will be offered soon. I discovered the problem back in March when I did a project where we virtualized a large amount of Citrix XenApp servers on an AMD platform with RVI capabilities. As Hardware MMU increased performance significantly it was enabled by default for 32Bit OS’es. This is when we noticed that large pages(side effect of enabling MMU) are not TPS’ed and thus give a totally different view of resource consumption than on your average cluster. When vSphere and Nehalem... [Lire la suite]
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10 juin 2009

vSphere ESXi on a USB memory stick

The procedure has not changed much since ESXi 3.5 but I thought I would document it anyway. A lot of people seem to end up here by googling “USB ESXi vSphere”. Here you go: First get the following tools: 7-Zip(Free), WinImage(Demo) Download the ESXi ISO (VMware-VMvisor-Installer-4.0.0-164009.x86_64.iso) Open the ISO with 7-Zip Open “image.tgz” with 7-Zip Browse to “\image.tgz.temptar\usr\lib\vmware\installer\VMware-VMvisor-big-164009-x86_64.dd.bz2\” Extract “VMware-VMvisor-big-164009-x86_64.dd” Open... [Lire la suite]
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