When backup of a System State is performed, a snapshot of data is created with the help of the VSS of System State. Several actions can lead to the error causing the snapshot loss:
- re-booting the server during the backup of System State;
- restarting the DataShield Back and Recovery service controller during the backup of System State;
- restarting VSS during the backup of System State.
In most cases this issue is temporary and the next backup will be successful.
NOTE: Also, the system can delete a snapshot by itself. Check event logs in the time frame +/- 10 minutes of the backup failure. In case VolSnap deletes the shapshot, you should tune your system to prevent that.