The Control Center displays the message "Other instances of db-backup must be running, exiting" when it fails to perform an unscheduled backup.

Following error messages are seen in the Control Center and in BrightmailLog.log:

Apr 25 2020 08:15:19 [http-41443-Processor6] ERROR - Cannot backup the database on the local host.
Apr 25 2020 08:15:19 [http-41443-Processor6] ERROR - ERROR: Other instances of db-backup must be running, exiting
Apr 25 2020 08:15:19 [http-41443-Processor6] ERROR -
com.brightmail.common.BrightmailException
        at com.brightmail.bl.agent.ScriptHelper.generateError(ScriptHelper.java:2743)
        at com.brightmail.bl.agent.ScriptHelper.backupDatabaseLocal(ScriptHelper.java:399)
        at com.brightmail.bl.agent.VersionManager.backupDatabaseLocal(VersionManager.java:175)
 

There is already another db-backup process running and a second backup process cannot be started.

This error indicates that a scheduled backup is already running in the background. 

Status of scheduled backups can be checked by looking at the "Scheduled Tasks Status" page (Status > Scheduled Tasks > Backups).

With large data sets which include logs, report data, and a large content quarantine it may take SMG a number of hours to complete a full backup especially if the backup is being stored remotely. Currently there is no mechanism to cancel a backup in progress.