Error Message

Error seen in Job Log -

Final error: 0xe000e20d - Backup job failed because one or more disks cannot access its parent disk.
Final error category: System Errors

For additional information regarding this error refer to link V-79-57344-57869

Backup- VRTSRV::\\10.10.10.10\Hyper-V?Virtual?Machine\HV19
V-79-57344-57869 - Backup job failed for disk 'H\CF2\C\Users\Public\Documents\Hyper-V\Virtual hard disks\Disk13.vhdx' because one or more disks cannot access its parent disk.

V-79-57344-57869 - Backup job failed for disk 'H\CF2\C\Users\Public\Documents\Hyper-V\Virtual hard disks\Disk14.vhdx' because one or more disks cannot access its parent disk.

V-79-57344-57869 - Backup job failed for disk 'H\CF2\C\Users\Public\Documents\Hyper-V\Virtual hard disks\Disk16.vhdx' because one or more disks cannot access its parent disk.

V-79-57344-57869 - Backup job failed for disk 'H\CF2\C\Virtual Machines\Win19_Gen2\Win2019_Gen2_Fixed.vhdx' because one or more disks cannot access its parent disk.

Or job completes with an exception:

Backup- VRTSRV::\\10.10.10.10\Hyper-V?Virtual?Machine\HV19
V-79-57344-38721 - Failed to mount one or more virtual disk images:
 

This issue is observed intermittently in the case of resource contention on a Backup Exec server.
 

Retry logic to access the disk resources has been added in Backup Exec 23.0 to minimize the occurrence of the issue. 
Additionally, the following registry key on the Hyper-V server is available to control the retry time interval if the issue continues.

NOTE: This registry is available in Backup Exec version 23.0 and above. 

Warning: Incorrect use of the Windows registry editor may prevent the operating system from functioning properly. Great care should be taken when making changes to a Windows registry. Registry modifications should only be carried-out by persons experienced in the use of the registry editor application. It is recommended that a complete backup of the registry and workstation be made prior to making any registry changes.

1.  Stop all Backup Exec services.

2.  Open registry editor. Navigate to
HKEY_LOCAL_MACHINE\SOFTWARE\Veritas\Backup Exec For Windows\Backup Exec\Engine\HyperV Agent

3.  Create a DWORD value ‘RetryDelayInSeconds’ and set it to 10
(Value can be set between 1 – 60 seconds) If the key or DWORD value is missing, create it.

4.  Start all Backup Exec services and re-run the backup job.