Posts Tagged ‘VSS’

Event-ID 25: Volsnap. The shadow copies of volume x were deleted because the shadow copy storage could not grow in time

August 5, 2011

I had a Windows Server 2008 R2 running Symantec BackupExec 2010 R2, doing Backup-to-disk-to-tape jobs daily, running fine for about 6 months. Then, for some reason the backups started failing on a part of the job.
Specifically, it failed on the part where it had to backup data from a local drive on the server (G:\) to the Backup-to-disk folder which was also on the same G:\ drive.
This had worked fine for quite a while, but somehow it started failing now, with the following error in the Windows Event Log:

Event-ID 25: Volsnap. The shadow copies of volume G: 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.

This would appear to be pointing to the drive not being able to handle all the IO traffice of reading from it, and writing to it at the same time. But it had worked for a couple of months before, so why would it suddenly not be able to handle this load then?
First i update BackupExec to the latest patchlevel. No difference.
Then i noticed there was not a lot of free space on the drive anymore, out of the 4 TB there was only 200 GB free space.
Maybe this wasn’t enough for BackupExec to be able to work with, so i cleaned it up to about 600 GB free space, and set the Minimum free space option for the B2D folder to 400 GB, so it would start removing old B2D files sooner.
After that, tried the backupjob again.
Still failed, with the same error. 😦
Then i did some reading on vssadmin.exe, and what can be done with it.
I used vssadmin to change the location of the shadowcopy storage.
This is where the vss service stores it’s temporary files while making a VSS backup of the drive.
The default location is on the drive itself.
So i changed this to another drive on the server which had about 200 gb of free space, and tested the backup again.
This time it worked! No more vss errors.
This change distributed the load of the VSS process amongst the 2 drives (read sourcefiles from G:, write shadowcopy of them to E:\, then write backup of E:\ to G:\B2D again), and the backup could successfully complete.