Scott Drummonds on Virtualization

x86 Über Alles


RISC is dead.  x86 is taking over the world.

At least that is how I read a press release from IDC dated 28 February, 2012.  Here are a few key points from the IDC statement:

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Maximum Hosts Per Cluster


I just returned from a one week vacation to a warm sunny beach on a small island not too far from Singapore.  Even on my vacations my conversations often migrate to technology and my travel mate is an old friend and current employee at VMware, Dave Korsunsky.  Sitting by a pool with a cocktail in hand at a fantastic hotel I asked my friend, “what is the right number of hosts per DRS/HA cluster?”  Great conversation for a vacation, right?

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Designing VMs with Performance SLAs


Consolidation amplifies the uncertainty of application performance. Still, VI administrators need a means of guaranteeing performance SLAs to their applications’ users. But the best VMware has been able to offer are resource controls, which are at best an indirect mechanism for sustaining application performance. With the acquisition of B-hive, now AppSpeed, VMware moved a step closer to allowing VI administrators to guarantee a performance SLA. As an application-aware latency measurement tool, AppSpeed may eventually provide feedback to vCenter to guarantee throughput levels. But it does not today. So how are VI administrators to guarantee application performance?

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How Many Virtual CPUs Per VM?


Virtual machine sizing is a tricky issue for many VMware administrators. It is important to find the right number of virtual CPUs to maximize application performance and minimize wasted CPU cycles. The optimal number of vCPUs can never be easily identified. But I can offer a few suggestions to help get this number right.

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Processor Utilization Calculations


A little Friday esxtop trivia for the performance massive: did you ever notice your Hyper-Threaded systems have three rows showing CPU utilization in the CPU panel header?  They are labeled “PCPU USED(%)”, “PCPU UTIL(%)”, and “CORE UTIL(%)”.  Here is a screen shot to jog your memory:

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Hyper-V's Lack of Memory Over-commit

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I find it interesting that one day after I wrote about memory over-commitment in vSphere, Greg Shields wrote about the lack of memory over-commitment in Hyper-V.  In today’s short blog entry, I want provide one paragraph that Greg’s article currently lacks:

While memory over-subscription is a critical feature for production environments, balancing the demands of heterogenous applications of varying demands in a resource starved environment is difficult.  Without guidance from administrators on the relative importance of the virtual machines running these applications, a hypervisor will be forced to make arbitrary decisions in assigning limited resources.  Effective use of over-commitment requires a sound resource control system.  The only product on the market that does this well is VMware vSphere.

Both Greg and my articles only talked of memory over-commitment, but the rules apply for CPU over-commitment, too.  Microsoft will realize how important resource controls are somewhere between year two and five of their product’s life.  I can only imagine where vSphere will be by then.

Hyper-Threading on vSphere


I continue to receive many questions from our customers on the expected performance gains of the new version of Hyper-Threading in Intel’s Core i7 processors. The answer requires a little bit of discussion on Hyper-Threading, a little bit on ESX, and comes with some performance data. If you are still interested, read on.

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Four Things You Should Know About ESX 4's Scheduler


[This is the last re-post of old community content.  But this content is important enough to be worth a re-post.]

I spend a great deal of time answering customers’ questions about the scheduler. Never have so many questions been asked about such an abstruse component for which so little user influence is possible. But CPU scheduling is central to system performance, so VMware strives to provide as much information on the subject as possible. In this blog entry, I want to point out a few nuggets of information on the CPU scheduler. These four bullets answer 95% of the questions I get asked.

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Newer Processors and Virtualization Performance


[New content has been added to this is an update to an old article from the performance community.]

Newer processors are much more important to virtualized environments than the non-virtualized counterpart. Generational improvements have not just increased the raw compute power, they have also reduced virtualization overheads. This blog entry will describe three key changes that have particularly impacted virtual performance.

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