You don't necessarily have to shut down the VM, but with just a simple snapshot the backup you take is a bit like pulling the power plug on the server. You'll get a good disk image, but you'll lose transactions in memory and just like with a hard power down there's always a chance of a database corruption. Shutting down the VM first would of course avoid the problem but that may not be an option for you if the DB server has to be up 24 x 7. If you want to avoid any change of corruption, then you might want to rely on another method for SQL backup (native file backups, agent based, etc). That way you'll have an extra safety net. Are you planning on using any backup software for this. Apps like vRanger will quiesce the file system and use VSS to quiesce SQL Server so that all writes get flushed out of memory and you should then have a crash consistant database. See this thread for a discussion on that. http://communities.vmware.com/message/741887