Scott Sauer recently asked me a tough question on Twitter. My roaming best practices talk includes the phrase “do not use PVSCSI for low-IO workloads”. When Scott saw a VMware KB echoing my recommendation, he asked the obvious question: “Why?” It took me a couple of days to get a sufficient answer.
February 4, 2010
January 26, 2010
VMware Perfmon Counters Missing on vSphere?
I was recently shown a problem where the ESX Perfmon counters we added to vSphere 4.0 virtual machines were not appearing in Windows virtual machines as of vSphere 4.0 U1. The problem stems from an issue with mofcomp, which I will briefly describe below. For the impatient, the workaround is to manually uninstall and then reinstall VMware Tools. It also appears that the counters can be added by running vmStatsProvider, as I described in a previous article.
January 21, 2010
VMware Performance Class: “VMware vSphere: Manage for Performance”
Nearly a year ago I approached the VMware Education Services about designing a single or multiple day class focused on performance management, troubleshooting performance problems, and designing solutions for maximum performance. I cited the perennial popularity of the VMworld performance troubleshooting lab as a demonstration of the potential market for this class. I am incredibly pleased to announce that the content for this class is complete and we are soon to be offering it to the general public.
January 15, 2010
Virtual Storage Design: Application Consolidation
Fixed recommendations for consolidation ratios are cancerous. Whether we are talking about vCPUs per core, virtual machines per host, or VMDKs per LUN, there is no single number the represents the “right” ratio. Accurate guidance requires workload characterization and fine tuning using vSphere’s performance counters. Today I want to highlight one experiment that shows application choice impacting VMDK-to-LUN consolidation. The inescapable conclusion is that sequential access data must be separated from random access files!
January 13, 2010
esxplot 1.0 Released
I am pleased to announce that Geoff White has completed the first official release of esxplot, version 1.0. In an earlier blog article we discussed a beta version of this product and the response from VMware’s customers has been fantastic. Those of you that have played with esxplot know its value in assisting with esxtop-based analysis. I urge everyone to download the new version and give it a try.
January 6, 2010
Optimizing Memory Utilization
My recent series of blog articles have discussed ESX memory management the the performance specter of host swapping. My last article attempts to correct the misconception that VMware recommends against over-commit memory. In that article I suggested that memory over-commit is requirement in optimizing memory utilization. Today I want to provide a specific example to show why this is true. I am have also included tips for identifying host swapping in your environments.
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January 4, 2010
Misunderstanding Memory Management
Twice in 2009 someone showed me competitive literature from Microsoft or Citrix claiming that VMware recommends against memory over-commitment. Given the wide variety of literature we have provided in support of this feature, all of our customers recognize the absurdity of our competitions’ claims. VMware and its customers love memory over-commitment. Then where is the source of this misinformed guidance?
December 24, 2009
Solid State Disks and Host Swapping
Recently I have been thinking, talking, and writing about ESX host memory swapping a lot. ESX swaps memory under the same conditions that traditional operating systems do; the application(s) is using more memory than available on the physical hardware. Host swapping is an unavoidable consequence of this condition, whether virtualization is present or not.
December 23, 2009
Your Performance Enemy: Host Swapping
Three times in the past week I have engaged in challenging discussions on host memory swapping and its impact to performance. If you read my article on host swapping and the whitepaper it summarized, you know the deleterious effect on performance caused by host swapping. When reading the paper, one of our most astute customers saw a sentence that gave him pause:
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November 18, 2009
Performance of Thin Provisioned Disks
I have received questions about thin provisioned disk performance since we announced their full support in vSphere. The questions usually center around scalability issues. VMware’s customers fear locking contention as new blocks are created for growing disks and think that growing thin disks may punish the performance of all virtual disks on a volume. Well performance engineering has finally released a paper on the subject and we are glad to say that thin disk performance is insignificantly different from thick disks.
