We have a Windows 2003 VM on ESX 3.5, running SQL 2005. Currently the VM has 4 drives, running on 4 separate vmdk files, on a single LUN. Additionally, the VM has a drive using a RDM hosted on a different LUN from the vmdk files. This server was configured in this fashion, to facilitate backing up the disks for the OS, database store, logs, and SQL backup folders with the Vranger product, as well as the fact that is being replicated offsite using LiveWire. The RDM partition contains scanned images, and will grow rather large. We didn't want this partition included in our VM backups, snapshots, or replication.

We hold licensing for EMC Replication Manager, and are considering implementing SAN snapshots for this VM. EMC is advising me that the RM will snap the entire LUN which would require that we partition about 400GB for the initial snapshot. I'm not sure we want to give up this much space on the SAN, as the actual data on the server is less than 40 GB at this point. As an alternative, EMC advised me to put each vmdk on a separate LUN, so that we could limit the snapshots to the database and transaction log files only. I guess another option would be to leave only the VM OS disk on a vmdk, and set up RDM for the remaining disks, so that the RM would truly be able to snap the changes only.

I'm looking for some input as to best practice.

Thanks.