On September 15th, VMware released a new whitepaper entitled “Microsoft Exchange Server 2010 Performance on vSphere 5.” If you are interested in virtualizing Exchange 2010 (or really any mission critical application) I’d recommend giving it a read.
One of the interesting things they’ve done in this test aside from scale up/scale out testing is to formally test vMotion and Storage vMotion during LoadGen. LoadGen, if you are unfamiliar, is a Microsoft tool used to simulate user activity in an Exchange environment and measure user response time.
I won’t spoil the ending of the report, but as expected the vMotion and Storage vMotion operations did not cause exceptions that would cause the LoadGen test to fail. In fact, the Storage vMotion had almost no impact whatsoever.
This brings up an interesting point – since VMware was able to prove that Storage vMotion caused no impact even during an Exchange performance test, it may be a good candidate for Storage DRS in vSphere 5. Microsoft has improved the I/O consumption of Exchange 2010 so much that it actually consumes very little I/O at all (relatively speaking compared to previous versions). Still, Exchange is a mission critical application and heavily utilized Exchange environments could benefit from Storage DRS migrating particular mailbox database VMDKs to less utilized storage to optimize the user experience. And as this whitepaper shows there is very little impact during the migration.
There may be reasons why organizations would chose to exclude their Exchange VMs from automatic Storage vMotion with Storage DRS. Some of those reasons could be around compliance, acceptance of this new vSphere 5 feature, concerns about performance, and possibly the impact on backup/DR strategies. Assuming those could be mitigated, I believe this testing shows that Exchange VMs actually make good candidates for Storage DRS.
I’m curious of what others think, so feel free to leave a comment.