During Hyper-V Agent Incremental backup to disk the job completes with the exception Failed to mount one or more virtual disk images. Hyper-V Agent full backups complete with no errors or exceptions.
V-79-57344-38721 - Failed to mount one or more virtual disk images:
V-79-57344-38725 - One or more virtual disks contain volumes that do not
support Granular Recovery Technology (GRT). Granular restores cannot be
performed for these volumes.
Invalid parameter was specified : Error writing file
Debug Log Backup Exec Media server:
Failed to OpenVirtualDisk rc=-1069940712 0xc03a0018
Retry attempt 1 for mount of E:\BEData\IMG001914\Virtual Files\C\ClusterStorage\Volume1\Virtual Machines\VM01\Vm01_Disk1.vhd
Full or Incremental Backup sets are being deleted by DLM (Data Lifecycle Management) in Backup Exec 2012 when a low disk condition threashold is encrouterd and the media retention period is over. Additionally manual deletion of Backup to disk files may cause this issue and the backup chain is missing backup sets.
NOTE: Hyper-V Backups require the whole chain of full-Incrementals backups. These backups must be maintained throughout the entire "one" chain of full-incrementals backups. This is true for both backup and restore because the data in these sets combine to generate catalogs for restore.
Run Full backups more frequently and retain them on disk so the incremental backups set dependency is retained.
Backup Exec 2012