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GRT Enabled HyperV backups Fail with Error - Failed to mount one or more virtual disk images:

Created: 06 Mar 2012 | 5 comments
HolgerMu's picture

Hello Folks,

I have an issue with GRT Enabled Backups on HyperV.

Environment is:

BackupexecServer: Windows 2008 R2 SP2 / BE2010 R3 SP2

HyperV: Windows 2008 R2 SP2

The Job can collect the Virtual Harddisk Image but then fails to mount the image to collect GRT data.

Error Code is:  V-79-57344-38721 - Failed to mount one or more virtual disk images

I have installed the Remote agent on all Virtual Machines, have confirmed the right user credentials. Confirmed that the Agents on the VM Report to the Media Server and they are listed under the "Favourite Ressources"

I tried to add the HyperV Role to the Media Server in case it was missing some Files needed to mount vhd images but no success.

Can someone point me into the right direction, I want to make sure I didn't forget anything simple before I call Support.



Comments 5 CommentsJump to latest comment

samueljn's picture

Is it failing on all the Virtual machine or any particular VM?

- If it is in one VM, check the writer status on the VM - vssadmin list writers

If it is in all the VM, then reinstall the Hyper-V agent

  • Tools - Install options - Remove the license - In the next screen, Uncheck Hyper-V from the options available for trial - Run through the set up
  • Re add the license and reinstall the Hyper-V agent
  • Run the backup
HolgerMu's picture

It fails on all Virtual Machines,

I reinstalled the HyperV Option/Agent and will wait for the backup to run tonight.

I will keep you posted


Holger Mundt | I.Tresor GmbH & Co. KG | Germany |

HolgerMu's picture

Unfortunately this did not solve the problem.

I Guess I have to go with Support since I went over and over the Admin Guide what I might have missed when implementing HyperV Backup

Or are there any other suggestions?


Holger Mundt | I.Tresor GmbH & Co. KG | Germany |

ZeRoC00L's picture

Do you have GPT partitions on the failing VM's ?

Check the Backup Exec Software Compatibility guide, Hyper-V VM GPT partitions are not supported.

If this response answers your concern, please mark it as a "solution"

HolgerMu's picture

nope, Basic MBR Partitions


Holger Mundt | I.Tresor GmbH & Co. KG | Germany |