Production checkpoints fail due to insufficient VSS Space

Question

Production checkpoints fail due to insufficient VSS Space

Arthur Maes 5

My Windows Server guest VMs fail to create Production Checkpoints because the hidden System Reserved partition doesn’t have enough free space for the VSS shadow storage area. The checkpoint process aborts with VSS-related errors, confirming that the shadow copy can’t be created in the reserved partition.

How can I redirect VSS shadow storage allocations to the C: volume so that checkpoint creation succeeds without resizing or modifying the System Reserved partition ?

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Answer 1

Hello Arthur,

The issue is exactly as you described: Hyper-V production checkpoints rely on VSS inside the guest, and by default the shadow storage is allocated on the same volume that hosts the system partition. On Windows Server guests, the hidden System Reserved partition is often too small to accommodate VSS snapshots, which causes the checkpoint creation to fail.

You don’t need to resize that partition. Instead, you can explicitly redirect the shadow storage to the C: drive. Run the following inside the guest VM with elevated privileges:

vssadmin delete shadowstorage /for=C: /on=C:

vssadmin add shadowstorage /for=C: /on=C: /maxsize=10%

The first command clears any existing shadow storage mapping. The second command forces VSS to use the C: volume as the storage location, with a maximum size allocation of 10% of the drive (you can adjust the percentage or specify an absolute value like 20GB depending on your environment).

After applying this, restart the VM and retry creating a production checkpoint. The checkpoint process should succeed because VSS will now allocate shadow copies on the C: drive instead of the System Reserved partition.

I hope you've found something useful here. If it helps you get more insight into the issue, it's appreciated to accept the answer. Should you have more questions, feel free to leave a message. Have a nice day!

HL.