Netbackup and VSS snapshots

[adamt078]

My server 2012 Netbackup client has VSS disabled in the OS However Netbackup is configured to use VSS for windows open files which is fine . I can see the vss snapshots being created and backup jobs running which is fine .. However Netbackups seems to be creating the snapshots randomly .. i.e Creating vss snapshots of D on E and all sorts ..

I think i need to force netbackup to create the snapshots on specified volumes .. i.e D on D ....??? or what is best practice as we now seem to be getting  the follwoing on the largest volume causing the job to fail 

The shadow copies of volume E: were deleted because the shadow copy storage could not grow in time.  Consider reducing the IO load on the system or choose a shadow copy storage volume that is not being shadow copied

or do I present a seperate volume say K and configure my 3 volume D , E and F to create my VSS snapshots on this dedicated K volume for VSS  ???

[Nicolai]

You can enfore VSS snapshots on a specific drive by using this T/N:

http://www.symantec.com/docs/TECH150413

[adamt078]

will having a dedicated volume for the VSS snapshot improve the speed of the backups ??

[Marianne]

No.
The location of snapshots will have no effect on backup speed. 

The main reason for slow backups is read speed of data from the disk where the data resides, not the snapshot. Could be bad LUN layout, fragmentation, millions of small files, high amount of directories and directory depth, etc....

Use the bpbkar test as suggested by Nagalla over here to test read speed from disk.

[sdo]

Hi - my two cents... Whilst it is true that using VSS won't speed up backups, it is worth mentioning that good configuration of VSS can avoid unnecessarily slowing down backups.  VSS is essentially a delta change log, thus it is possible that if a large/complex drive is being backed-up, and VSS is being used, and this drive has a reasonable to high rate of data change (writes), and the VSS snapshot has been assigned to the same disk - then I would fully expect to see the backup slow down considerably.  For large complex servers and drives with a reasonable amount of writes I would certainly consider having additional drives/LUNs presented (on different buses, ports, raid groups, storage) for use purely as VSS delta change space during backups.  In fact for very large servers, even if you can't present additional storage for purely VSS space, then judicious use of multi-streaming and max jobs with well configured VSS (i.e. each drive to be backed-up assigned a different drive (that won't yet be being backed-up) for VSS) can avoid unnecessary impact - and even increase the chances of successful backups using VSS (not withstanding the client attribute of continue on snapshot error).  HTH.

[sdo]

Final point - the above would be true for any backup product that utilises VSS - it is not NetBackup specific.