I have a couple of OES2 sp3 servers running in VM that have terrible backup performance (1.2GB/hour) when backup up the nss volume which is connected in the vm through iscsi. The linux file system which resides in vmdk file on the same san backups up fine (20GB/hour).

These servers are running multipathd and the file access performance during the day to these volumes are fine, I can copy a 2.25gb file to the nss volume in under 7 minutes, it seems the issue is only when the tsa backup agent is working.
I am running commvault 9 backup agent.

Also I have very similar set ups in other locations with are OES2 sp2 servers and the performance is 10x faster on the nss iscsi volume.

Any thoughts?