Problem with VSS

[EduardoDiaz]

Hi,

I have a windows machine that started failing the backups because of the VSS service.

The log files say:

VSS_CREATE Creating a shadow copy of C:
IVSASYNC_TIMEOUT IVssAsync is pending for more than 60 seconds
VSS_SNAPSHOT Shadow copy creation failed: DoSnapshotSet didn’t finish properly
Shadow copy creation failed: DoSnapshotSet didn’t finish properly

In the EventViewer I can see

IVssWriterCallback HR=0x80070005 Access denied

How can I diagnose/solve this issue?

best regards

[Droolio]

I’ve had this problem before (on an old PC) - where VSS snapshotting takes longer than the default timeout of 60 seconds. If this isn’t just a corrupt VSS store, it just means it takes a long time to do snapshots - which can definitely happen on old systems with a lot of files and snapshots.

My solution at the time was to add the -vss-timeout 90 flag to the backup command.

You may have to increase it to 120 or more, if necessary. If your backup completes with an increased timeout, that’ll be your issue. And while you can keep the flag, you might want to investigate why VSS is taking so long (because under normal circumstances it should take a few seconds.)

There are various tricks to reset or clear the snapshot list and you might get a fresher experience (I’m afraid I don’t remember the exact commands so you’d have to look those up yourself.) Most likely it’ll reoccur over time, because you have lots of files, and/or a slow system (like a heavily fragmented HDD instead of a SSD).

[EduardoDiaz]

Many thanks! That did the trick. My backup has progressed to “indexing…” so I expect it to finish without further problems.

I certainly noticed that the C unit is slow to make snapshots. Even manual snapshots take much more time than E, for example. I will try to get some further diagnostics now that I know I have a backup.

Best regards.