I'm using BackupExec and VCB to backup a few VMs. As I understand it, the pre-job script creates a snapshot of my VMs, mounts them as virtual directories on my backup server, and then my backup exec job just backs up the local folders like normal. The problem I'm having occurs during the pre-job script and the directory for one particular server is never mounted.
When I look at the VI client and look at recent activity, I see the snapshot has begun but hasn't finished. It appears to time out after 15 minutes, and thus the server is never backed up.
I have multiple VMs being backed up this way and the others work fine. The troublesome VM has a virtual disk of 85GBs, however, another VM that does work has a virtual disk of nearly 100GBs.
I'm wondering what else about a VM could cause the snapshot to take a long time to create. Is it an issue with the VM host perhaps? The VM host is a very powerful server, and none of the VM guests are used heavily, plus the backups are run off-hours so it shouldn't be a case that the server is just overworked. Are there any logs or tools I can use to see what's slowing the snapshot down?
Best Answer
VMWare uses the term snapshot rather loosely. It is not actually creating a copy of your server, what it does is to stop making any changes to the existing diskfile - and redirect the changes to a delta file for the life of the snapshot.
What this means is:
I think that what the VCB process does is to make a snapshot (so that the data doesn't change during the copy), and then make a clone of the frozen file for backing up. This can take some time - although you mention that it succeeds for a larger server, so this probably isn't the issue.
One possibility is if you have any virtual disks marked as independent. If so, these are ignored by the snapshot process, and possibly by VCB as well. Not sure how VCB mounts the drives, but perhaps it requires a drive that is marked as independent?