Restore of file/folder GRT data from an incremental backup set fails with the following error:
V-79-57344-38721 - Failed to mount one or more virtual disk images
This error occurs if the following tasks were performed in the order listed:
- Created a file/folder GRT-enabled backup of a Hyper-V virtual machine and used the option "Back up to tape and then duplicate to disk".
- Ran the full backup and then the duplicate job.
- Added a new vhd or vhdx disk to the virtual machine.
- Ran the incremental backup and then the duplicate job.
- Created a restore job to restore GRT data from the newly added vhd or vhdx disk from the incremental backup set on disk storage.
The error occurs because the duplicate job from tape to disk does not have any metadata to verify if the disk was added before the incremental job. So the newly added disk is created as a differencing disk during duplicate job, however it should be created as a fixed/dynamic disk. During the restore job, the mounter finds the type of the disk as differencing. Since this is unexpected, the job fails.
Restore the data from the incremental set on tape storage instead of from the disk storage.