NetWorker: NMM Hyper-v support for VMs with user checkpoints
Summary: Previously RCT backups would fail if the VM has a user checkpoint with error: "Reason: Saveset contains VM with checkpoint" Starting NMM 19.8, you can perform RCT backups (full or incremental) and recoveries of a virtual machine with multiple user-checkpoints present. The Hyper-V Manager displays all the checkpoints of a virtual machine. Granular level recovery (GLR) enables you to recover specific files from a single backup without recovering the full virtual machine. ...
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Symptoms
NMM mounts the virtual machine.
After the mount operation succeeds, in the middle panel, on the Browse tab, select the mounted virtual machine.
The list of the VHDs that the mounted virtual machine contains appear in the right panel.
When the virtual machine has user checkpoints, you notice missing folders/files.
That is to say not to see all changes are seen in the virtual machine.
After the mount operation succeeds, in the middle panel, on the Browse tab, select the mounted virtual machine.
The list of the VHDs that the mounted virtual machine contains appear in the right panel.
When the virtual machine has user checkpoints, you notice missing folders/files.
That is to say not to see all changes are seen in the virtual machine.
Cause
Hyper-V users can use the Hyper-V management interface to create checkpoints for a virtual machine to capture the virtual machine state at strategic points of their own choice.
Hyper-V checkpoints are of two types:
- Backup checkpoints.
- User created checkpoints.
User checkpoints can be created from the PowerShell or Hyper-V manager. However, there are no options to create backup checkpoints in the Hyper-V manager. They are supposed to be created by backup applications, which are merged once backup completes. This is to provide consistent backup of the VHDXs.
Both these types of checkpoints create differencing disks that provide rollback capabilities to these strategic points.
Differencing Virtual Hard Disk: A virtual hard disk file that represents the current state of the virtual hard disk as modified blocks in comparison to a parent virtual hard disk file.
Any new write to the virtual disk is captured in the latest child virtual hard disk.
i.e All data changes to the virtual machine go to the differencing disk (AVHDx).
However the parent disk (VHDx) and the tree of differencing disks (AVHDx) should be accessible to the Hyper-v Manager.
This differencing disk gets merged to its parent disk; Hyper-V merges the .avhdx and .vhdx files when checkpoints are deleted.
During RCT backup of virtual machine with user checkpoint, NMM backs up the virtual machine configuration file, Parent Disk (VHDx) and all user checkpoints (AVHDx).
During GLR Mount of RCT Backup, NMM mounts the Parent disk (VHDx), NMM cannot merge the disks for you (Parent Disk (VHDx) and all user checkpoints (AVHDx)), hence you will not see all changes done in the Virtual machine after user checkpoint creation.
Reference:
https://learn.microsoft.com/en-us/virtualization/hyper-v-on-windows/user-guide/checkpoints
Resolution
If a VM has user checkpoints, then VM image restore would be supported.
Run Image restore with rename VM, all user checkpoints are restored as well.
You can open the new VM and see all changes that were made,
If the user checkpoints are no longer needed, then delete the checkpoints.
Run Image restore with rename VM, all user checkpoints are restored as well.
You can open the new VM and see all changes that were made,
If the user checkpoints are no longer needed, then delete the checkpoints.
Article Properties
Article Number: 000218333
Article Type: Solution
Last Modified: 17 Jul 2025
Version: 3
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