Resetting CBT After Restore

[JPMS]

Every single time I restore a VM I get the following error when I next run a backup:

Cannot use CBT: There is no change tracking data available associated with the specified change tracking identifier.. Failed to query changes for disk ...

I know how to reset the CBT but why doesn't B&R do it automatically when it performs a restore?!

[DGrinev]

Hi,

That's expected behavior. It's happening because of automatic CBT reset after each restore, that's needed for consistent backup creation afterward.
Can you confirm that only the first backup run after the restore operation provides with this error?

Thanks!

[JPMS]

I'm a bit confused about this!

You say that there is an automatic reset after each restore, so why does the error occur on the first backup after restoring?

Also, I don't believe it happens only after the first backup. I think it reoccurs until I run Reset-HvVmChangeTracking. This is from memory as I now always run Reset-HvVmChangeTracking when I get the error so I don't wait for a second backup before I intervene.

[DGrinev]

The warning occurs because of the CBT reset to notify you that CBT won't work for the particular run.
Can you test if there is no warning appear on the subsequent run?

Thanks!

[Egor Yakovlev]

Hi JPMS,
Just to make it clear:
- VM Restore using "...to Original location" will [delete] production VM, and recreate it from backup. VM UUID will be the same, but VHDX disks will be [new] files, created from the scratch using backup data. That's why you will see "no change tracking data..." warning, because those are [new] disks on [old] VM. This is your case.
- VM Restore using "...to Original location + [x] Quick Rollback checkbox" will actually transfer only changed blocks of VHDX files, so VM disk files are not deleted\recreated and remain the same, no matter of it's content changes. This case will trigger CBT just fine and Veeam job will continue to run Green.
- VM Restore using "...to a New location" will create a brand new fresh VM with no CBT data logged, and job will work all-green like normal.

Summary:
- ignore CBT warning on first job run after Full VM Restore - incremental backup runs will be "green"
- restore your VMs using "Quick Rollback" option, and you won't see CBT warning anymore
- Quick Rollback will be faster - way faster than Entire VM Restore! (if corrupted production VM is still there on a disk)

/Cheers!

[JPMS]

Thanks for the replies.

Yes Egor, you are correct, I'm performing a restore to original location without utilising Quick Rollback. Thanks for the explanation of what is actually happening with the different types of restore.

Can I just clarify then. With this sort of restore, should the warning disappear after the first subsequent backup? (I don't think it does but I will have to test). Or do I need to reset manually as I am doing? In which case, I go back to my original question, why doesn't B&R do this automatically?

Thanks, Jason

[DGrinev]

Starting from the second backup session, you shouldn't see the warning message.

Thanks!

[JPMS]

Thanks. I'll test and post the result.