Limitations

  1. Backup of VMs located on a SMB 3.0 shares is not supported.

  2. Backup of guest VMs with pass-through disk (directly attached physical disk) is not supported. This is a Hyper-V limitation as the Microsoft Software Shadow Copy Provider cannot provide AhsayOBM with a VSS snapshot of pass-through disks which is required for a guest VM backup.

    Although guest VM level backups are not possible, it is recommended to install AhsayOBM directly onto the guest VM to perform backups.

  3. For backup of individual virtual disks, the restored VM does not support the reversion of previous snapshots, if the snapshot contains disks which are not previously backed up by AhsayOBM.

  4. A guest VM can only be restored to the Hyper-V server with the same version, e.g. backup of a VM on Hyper-V 2012 R2 server cannot be restored to Hyper-V 2008 R2 Server or vice versa.

  5. The VM will not start up if the virtual disk containing the guest operating system is not restored.

  6. Restore of individual virtual disks is only supported using the Restore raw file option for a virtual disk with no snapshots.

    This will require modification of Hyper-V guest configuration files, and this only should be done if you have in-depth knowledge and understanding of Hyper-V, otherwise the guest VM may not startup properly.

  7. Replication must be disabled for the VM selected for backup, otherwise the following error may occur during the backup job:

    
Error
Failed to backup virtual machine "guest_guid"., Reason = "Failed to take VM snapshot. Error =
[CreateVirtualSystemSnapshotV2] Error="The method call failed." (32775)".

Resolution
To resolve the issue, disable the replication of the vritual machine selected for backup. Click here for instructions.

Run Direct Restore

Run Direct Restore of VM containing VHDS shared virtual disk(s) is not supported.

Granular Restore

  • Granular restore does not support the mounting of virtual disks, if the disk itself is encrypted, for example using Windows Bitlocker or other third-party security features.

  • If any folders or files on a virtual disk are encrypted these files/folders cannot be restored. For example, if the “Encrypt contents to secure data” is selected in Advanced attributes.

  • The mounting of Linux/Unix file systems from virtual disk file is currently not available due to limitations of the file system drivers.

  • Granular restore can only be performed on one guest VM at a time with no limitation on number of virtual disk than can be mounted on the guest VM. However, only files/folders from one virtual disk can be retrieved at a time.

  • Windows User Account Control (UAC) must be disabled to apply Granular Restore.