From Virtualization.info

VMware published a new 12-pages precious paper describing how VirtualCenter performs when using a Microsoft SQL Server 2005 back-end database, and how it should be configured to achieve optimal performance.

The VirtualCenter database saves performance history for all the managed VMs, which is a pretty intensive I/O activity, so the test methodology measured how well SQL Server 2005 performs in a virtual environment with 100 VMs.

Download document here…