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This week I wrote a follow up story on VMware Inc.’s virtualization performance benchmarking tool, VMmark, and found it is mainly used by vendors as a way to market their servers.
Server vendors run the VMmark test under a set of guidelines and submit results to VMware for posting. It is my suspicion that vendors play leapfrog with VMmark by looking at exsiting VMmark results and only submitting their performance results when theirs are as good or better.
For instance, IBM submitted a benchmark for its 16-core System x3850 M2
running VMware ESX v3.5, which trumped the other published as of March 2008. IBM then published a press release to brag about the results, but within a few months, Dell submitted results three PowerEdge systems sporting better virtual machine (VM) performance than IBM, and Hewlett Packard (HP) beat them all out with its ProLiant DL585 G5 server results published August 5.
HP also sent out an email to press this week boasting their top 32-core results, but didn’t mention one minor detail; they are the only vendor with results in the 32-core category so far. Sure, they are number one. They are the only one.
System Administrator Bob Plankers sums this game up nicely in his blog with a post called “Why VMmark Sucks.” Here is what Plankers had to say:
“Having a standard benchmark to measure virtual machine performance is useful. Customers will swoon over hardware vendors’ published results. Virtualization companies will complain that the benchmark is unfair. Then they’ll all get silent, start rigging the tests, scrape and cheat and skew the numbers so that their machines look the greatest, their hypervisor is the fastest. Along the way it’ll stop being about sheer performance and become performance per dollar. Then CapEx vs. OpEx. Watt per tile. Heat per VM. Who knows, except everybody will be the best at something, according to their own marketing department.”
In addition, the benchmark is a real pain to set up and run, and the ‘free’ VMmark software requires other expensive software to work. According to VMware’s website,
VMmark requires licenses for the following software packages;
- Microsoft Windows Server 2003 Release 2 Enterprise Edition (32-bit)—thre 32-bit copies per tile (two for virtual machines and one for that tile’s client system), and one 64-bit copy per tile (for the Java server virtual machine)
- Microsoft Exchange Server 2003 Enterprise Edition
- SPECjbb2005 Benchmark
- SPECweb2005 Benchmark
Plankers said he won’t be wasting any time or money running VMmark. “Instead, I’ll be in meetings explaining to folks why we are maxed out at 30 VMs per server when the vendor says they’ll run 50. Or why we chose VMware over Xen, when Xen claims 100 on the same hardware. I’ll have to remember the line from the FAQ that says “that VMmark is neither a capacity planning tool nor a sizing tool.”
Which begs the question: if it isn’t for use in sizing or capacity planning, exactly what is it good for?”
VMware says the benchmark is good for users who are making hardware purchasing decisions.
“The intention [of VMmark] is that customers can look at the results and make decisions based on what they see. It isn’t just about the fastest server; it’s about making system comparisons; between blades and rackmounts or a two-core or four-core system. Someone can see how much more performance they get from upgrading to four core processors, for instance,” said Jennifer Anderson, the senior director of research and development at VMware.
This makes sense, but as Plankers said, users should beware of benchmark manipulation by vendors and know that the results do not reflect the same workloads that users will run in their own data center environments.