I recently wrote a blog article detailing Hyper-Threading (HT) and its effect on vSphere. An astute reader pointed out, a recent update to Project VRC’s terminal services analysis suggests disappointment with HT on vSphere. We spent a lot of time looking at those results to understand why they contradicted the body of performance data, which show HT offering 10-30% gain on vSphere. What we discovered led us to create a vSphere patch that would allow users to improve performance in some benchmarking environments.
March 17, 2010
March 6, 2010
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.
March 3, 2010
Maximum Concurrent VMotions
A VMware customer and attendee of a talk I gave at a performance roundtable asked me for a preview of unreleased features*. When I talked about the amazing improvements to VMotion that would enable as many as eight concurrent VMotions the customer said, and I am paraphrasing here, “Yawn. I can already do that.” Really? I had no idea customers could do this. As it turns out, many of us at VMware did not know that customers knew how to do this.
March 1, 2010
Memory Compression
Steve Herrod’s keynote at Partner Exchange 2010 included a tantalizing slide on an upcoming memory maximization technology: memory compression. A few of you have already seen the overview of this technology Kit Colbert and Fei Guo previewed it at VMworld 2009. Today I want to tell you how this upcoming feature will help you pack even more virtual machines onto your existing servers.
February 22, 2010
PVSCSI and vmxnet3
I heard a myth today that VMware did not support running vmxnet3 and PVSCSI in the same virtual machine. I have talked with a dozen engineers on the subject since it came up this morning and all swear the drivers run great together. The two drivers work on very different and unrelated stacks in the VMkernel. There are no inter-dependencies of any sort between PVSCSI and vmxnet3.
I think this rumor sprung from our somewhat limited support of paravirtualized drivers in FT-protected virtual machines, which will be improved in a subsequent release. And while most of you probably know that PVSCSI and vmxnet3 run together, I thought it worth a brief comment on this blog. Myths are like cockroaches. For every one you see there are hundreds hiding behind the walls.
February 18, 2010
VMworld 2010 Performance Lab
As you can imagine, we VMware employees are starting to ramp up for VMworld 2010 and its younger brother in Copenhagen, VMworld Europe 2010. Last year I ran the performance lab and this year I plan on making it even more awesome than last year. Since this blog enjoys a small following of the performance faithful and VMworld attendees, I want to put the question to you: what do you want to see in the upcoming performance troubleshooting lab?
February 12, 2010
Windows Guest Defragmentation
Today at VMware Partner Exchange I had a lunchtime discussion with a partner of ours that makes a Windows file system (NTFS) defragmentation tool. He related anecdotes of incredible performance acceleration credited to defragmentation and quoted a few numbers based on his test environment. When he asked me what VMware’s recommendations were on the subject I remained uncharacteristically silent. Do we have best practices on this?
February 11, 2010
Las Vegas Taxi Rates
Let’s take a break from virtualization and talk about taxi cabs in Las Vegas. I just got into McCarran airport after a fantastically successful VMware Partner Exchange 2010 and want to ask some of you seasoned veterans of Las Vegas to share your thoughts on a cab problem that I only learned of today.
February 10, 2010
Inaccuracy of In-guest Performance Counters
Every couple of months I receive a request for an explanation as to why performance counters in a virtual machine cannot be trusted. While it is unfairly cynical to say that in-guest counters are never right, accurate capacity management and troubleshooting should rely on the counters provided by vSphere in either vCenter or esxtop. The explanation is too short to merit a white paper but I hope a blog article will serve as the authoritative comment on the subject.
February 4, 2010
PVSCSI and Low IO Workloads
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.
