Challenge
A backup job for a VM in Hyper-V fails after 72 hours with the error:
Failed to call RPC function 'HvSetVmBackupStatus': Snapshot with id '{snapshot-uuid}' was not found.
In the Task log for the specific VM ( %programdata%\Veeam\Backup\<jobname>\Task.<vmname>.<vm-uuid>.log ) the following error is found:
Error The device is not ready. (Veeam.Backup.Common.CCppComponentException)
Error Failed to read data from the file [\\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy3\<foldername>\<vmname>\Virtual Hard Disks\<vmname>.vhdx]. (Veeam.Backup.Common.CCppComponentException)
In the Svc.VeeamHvIntegration.log log file found on the Veeam Backup & Replication server ( %programdata%\Veeam\Backup ) the following is found:
WARN|[GC] Removing expired snapshot. Creation time: '<date-stamp>'. JobInfo: 'Locked Job [<jobname>], Backup console [<veeamservername>]'. Is successful snapshot: 'true'. Is completed: 'true'. Life time: '72' hour.
Cause
This failure occurs due to the Veeam Backup & Replication built-in 'snapshot life time' limit of 72 hours.This limit is intended to prevent issues with VM performance due to being on a shadow copy for extended periods of time.
Solution
The first goal of resolving this should be to determine if any performance improvements can be made to cause the VM to complete being backed up within 72 hours.
If it is not possible to improve performance, the 'snapshot life time' limit is adjustable with a registry entry on the Veeam Backup & Replication server:
(The Veeam Backup Service on the Veeam Backup & Replication server must be restarted after the key is modified to take immediate effect)
Location: HKEY_LOCAL_MACHINE\SOFTWARE\Veeam\Veeam Backup and Replication\
Type: DWORD
Name: hvSnapshotLifeTimeHour
Value: 72
The value may be doubled or set to a value which is sufficient to allow the VM to complete being backed up.
It is inadvisable to set the value any higher than 240 unless absolutely necessary, and should never exceed 596. In most cases a value of 144 (double default) works fine.