Backup Job Fails with Mutex Error

Article ID: DD0022 Version 9 Backup Jobs fails with Mutex Error when accessing the Deduplication Database (DDB).

Symptom

Mailbox, DDB Subclient, or Virtual Server Agent backup job fails.  Search of job relevant backup process logs finds mutex errrors similar to the following:

6504 111c [date/time] 12173 QuiesceEngines: Unable to lock mutex [DDB Path]. Error [lock(): Internal CNamedMutex error: m_hMutex = NULL][-1]

13052 2660 [date/time] 32466 LaunchSidbLocal: Cannot Create CVD-SIDB2 mutex. Error [5][CNamedMutex(): Mutex handle was not created or opened]

4941 405da940 [date/time] 2892077 Failed to lock the mutex. Will have to shutdown. Return code -1. Error code = -4, CvFileLock::lock(): Unable to open lock file /tmp/cldbenginemutex_859856-257155_7188_0: Permission denied.

 

Cause

Applies only to Commvault Version 9

DDB Backup (System User) and Exchange Mailbox iDataAgent/Virtual Server Agent Backup (User Impersonation) processes are running on the same host under different user authority while trying to simultaneously access a SIDB-Mutex object (DDB) . This is creating a user context conflict where the DDB Backup is unable to quiese the DDB for backup or the Agent backup is denied access because DDB Backup has quiesed the DDB.

In Commvault Version 10, all access is managed by a single process (CVD).

Resolution

Applies only to Commvault Version 9

Disable Source/Client-side deduplication for all Virtual Client or Exchange Mailbox iDataAgent subclients hosted by and configured to use the MediaAgent hosting the DDB. As the Agent and MediAgent are on the same host, disabling Source/Client-side deduplication and using MediaAgent deduplication will force all DDB access to a single process (CVD) avoiding the mutex error.