We currently have Vcenter installed on a VM. On a separate MSSQL server VM we have the Vcenter database. We use VDR 2.0 to backup the MSSQL server. The problem is if the MSSQL server crashes or needs to be recovered we can't because the Vcenter database is on the mssql server. I'm sure others have had this problem. Both servers are windows server 2008 running on ESXI 5.0.
To sum it up the MSSQL server can't be recovered by Vcenter because it contains the Vcenter database. So when the MSSQL server is offline so is the Vcenter.