So I recently fired up a few new virtual machines in my 2008 R2 Hyper-V cluster for a new project I’m working on. Got everything up and running and set up the new VMs on a backup schedule in Backup Exec. The next morning I went to check to make sure the backups happened correctly, and was greeted with this error:
V-79-57344-38721 – Failed to mount one or more virtual disk images
So the VMs backed up, but the GRT (granular restore) portion of the backup failed, and I wouldn’t be able to recover individual files from the VMs. Searching through Symantec’s KB articles was less than useful (as it often is) so it seemed I had to figure this out myself.
I went over everything I did and didn’t come up with any variation on my normal procedure for creating VMs. However, I realized that these are the first VMs I had created since I upgraded to SCVMM 2012 SP1 from 2008 R2, so perhaps something changed there. I do know that if you’re creating a VM in a cluster, you no longer get prompted to make it highly available, that’s now a checkbox, and if you forget it, the VM creation fails, so that seemed like a good place to start. Well, after checking Event Viewer logs, which were of no help.
So I stepped through the process of creating a new VM in SCVMM paying very close attention at each screen to see if there may have been something I missed. Everything looked good until I got to the Configure Settings portion of the wizard, and I noticed that the vhd files no longer get placed in the same folder as the configuration files by default, they were going to the default storage location for the server they were being created on. So I checked there, and SCVMM had created a VMMDisks folder and all the vhd files for the new VMs were there.
Well, there was something different. So using the Migrate Storage option, I moved the vhd files for one of the VMs back into the folder where the configuration files were and reran the backup job. And no more GRT error.
So it would appear that Backup Exec 2010 R3 is not capable of doing a Hyper-V GRT backup if the vhd files reside in a folder other than where the configuration files are. I’ll just have to make sure I’m manually setting them up in the right place going forward.