Sir Slicendice (1/8/2009)
In my experience, the benefit of virtualization for SQL server is how much you are willing to trade off improved management for performance.But depending on the workload, the performance giveup can be huge: as an obvious case, you generally loose the ability to map SQL server partitions to spindles, which will crush performance if your partitions are properly designed.
This boils down to implementation and how you have structured your infrastructure early on. The SAN LUNS I have are dedicated to SQL, and at the console level of ESX we can see what the IO being done by that LUN. I have a 300GB data warehouse on VMware that runs just fine, in fact I have less problems from it because it is designed properly than I do from some of our < 2GB databases on physical hardware that have bad designs. One of the < 2GB databases was moved off of VMware because the vendor refused to support it on a virtual machine because that was the problem. Now on a dedicated 2 processor 4GB RAM x64 Physical Server and it still won't perform, and the database is small enough to exist completely in the Buffer Cache.
You can certainly track performance in ESX if you plan your infrastructure properly.
Jonathan Kehayias | Principal Consultant | MCM: SQL Server 2008
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