31418: Acronis Backup: Backup Fails with ''Not enough space to create a volume snapshot on the volume where the snapshot storage is set"

Increase the storage size or change the storage location of the volume snapshot


Disk/partition or file-level backup fails with the following error:

Not enough space to create a volume snapshot on the volume where the snapshot storage is set.


Insufficient storage available to create either the shadow copy storage file or other shadow copy data.


There is not enough space for the snapshot storage.

Once a snapshot is created during backing up, all the subsequent I/O operations are cached in a temporary storage called snapshot storage. If the amount of I/O operations is too large, the space for caching them can end.


One of the ways to avoid this issue is to perform backups when the I/O load is lower.

You can also free up space on the disk, increase the snapshot storage size or move the storage to a volume with more free space.

Acronis uses the same drive to create a shadow copy by default if VSS is enabled. Moving VSS Shadow Storage can be useful if you need to:

  • Use a different drive with more free space available to create a snapshot
  • Distribute the snapshot I/O load to a different drive on production devices
  • Perform a successful snapshot of a disk that may be damaged

Acronis Backup Cloud and Acronis Backup 12.5

Microsoft VSS provider by default uses the same volume for storing snapshots with the small Maximum Shadow Copy Storage space parameter value.

The vssadmin command line tool should be used to check and configure the VSS storage parameters.

First you will need to list the shadow storages by using the vssadmin list shadowstorage command. See also Microsoft TechNet: Vssadmin list shadowstorage.

In the command line (Start-Run -> cmd), issue the following command:
vssadmin list shadowstorage

You will get the list of associations:

For volume: (C:)\\?\Volume{34e2a3b2-3136-11df-81bf-806e6f6e6963}\
Shadow Copy Storage volume: (C:)\\?\Volume{34e2a3b2-3136-11df-81bf-806e6f6e6963}\
Used Shadow Copy Storage space: 1.815 GB (1%)
Allocated Shadow Copy Storage space: 2.315 GB (1%)
Maximum Shadow Copy Storage space: 2.419 GB (1%)

(!) If no shadow storages are specified, the operating system defines the volume to store snapshots automatically.

If the volume that you back up has enough free space to store the snapshots, you can resize the shadow storage with the vssadmin resize shadowstorage command. See also Microsoft TechNet: Vssadmin resize shadowstorage.

For example:
vssadmin resize shadowstorage /for=c: /on=c: /maxsize=20GB

(!) If you would like to allocate all of the volume's free space for the storage, use the unbounded value. E.g. vssadmin resize shadowstorage /for=c: /on=c: /maxsize=unbounded

You can also do the resize via Computer -> Properties -> System Protection. For details please see External Resource: Change & Limit System Restore In Windows 7.

If you need to change the current volume of where the storage is to a different one, you can do this on server operating systems with the vssadmin delete shadowstorage and vssadmin add shadowstorage commands. This will delete the current shadow storage and create a new one on the volume you specify. See also Microsoft TechNet: Vssadmin delete shadowstorage and Vssadmin add shadowstorage.

Only server operating systems support the Shadow Copy transporting functionality.

For example:
vssadmin delete shadowstorage /for=c: /on=c:
vssadmin add shadowstorage /for=c: /on=d: /maxsize=20GB

As a result, all snapshot data of volume C: will be cached on volume D:.


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