Acronis Cyber Protect: Backup finishes with warning "Failed to read the snapshot of the machine because the snapshot no longer exists"

Acronis Cyber Protect: Backup finishes with warning "Failed to read the snapshot of the machine because the snapshot no longer exists"

Symptoms

Backup finishes with the following warning during backup:

Failed to read the snapshot of the machine because the snapshot no longer exists

HideExample of full error message: click to expand

 

Error 0x950211: Failed to read the snapshot of the machine because the snapshot no longer exists. Trying to create a snapshot again. Retries left: 2
| trace level: warning
| line: 0xce47d41ec1026d76
| file: d:\1737\enterprise\disk_manager\daapi1\disk_manager_impl.cpp:1183
| function: DiskManagement::Da1DiskManagerImpl::Perform
| $module: disk_bundle_vsa64_26986

Cause

The warning occurs if there is not enough space in shadowstorage for snapshot growth, and therefore the snapshot is deleted automatically

Starting from Acronis Cyber Cloud 21.09 this message is information-level instead of a warning.

Solution

This warning can be ignored, as it does not affect the backup validity.

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

You can also free up space on the source disk or move the storage to a volume with more free space (on server operating systems only).

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

HideHow to move shadowstorage: click to expand

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.

On server operating systems you can change the current volume of where the storage is to a different one 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 shadows /for=c:

Note that the above command deletes all shadow copies of the volume

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: