If you’ve added a volume to a VMware Data Recovery appliance you’ve probably read the part of the Administration Guide entitled “Add a Hard Disk to the Backup Appliance,” especially page 18 where it says:
If creating a SCSI virtual disk, it is recommended that you set the SCSI value to SCSI 1:0.
When you specify a SCSI Virtual Device Node the numbering scheme is Bus:ID, so what they’re really recommending by suggesting 1:0 is to let vSphere create another virtual SCSI controller. By default, that new SCSI controller will be set to “LSI Logic Parallel.”
What I’ve noticed, though, is that the VMware Data Recovery appliance has the pvscsi modules installed, so you can change the type of SCSI controller to “Paravirtual” and take advantage of the performance gains. Nothing is mentioned in the documentation, pro or con, but it’s been working for me under VDR 1.1 and now under VDR 1.2. I’ll certainly take the free performance boost, especially on an I/O intensive VM!
Thanks for the tip. I’ve been experimenting with VDR, but I haven’t pushed its documented bounds other than upgrading the appliance to 4vCPU/4GB RAM.
PVSCSI is not necessarily will give you better performance:
http://kb.vmware.com/kb/1017652