You can configure the Commvault software to always run a copy-only full backup for an Always On availability group instance. A copy-only backup is an independent backup that you can perform on any secondary replica in an availability group.
You can perform copy-only backups of availability groups for special purposes, without affecting other backups or restores. You can perform the following backups as copy-only backups:
Full Volume Shadow Services-enabled backups
Full IntelliSnap backups
When you run a log backup after a copy-only full backup, the log backup is automatically linked to the copy-only full backup and follows the retention rules of the copy-only full backup. If there are any missing logs during the log backup, the next backup operation is automatically converted to a regular full backup. If you want converted backups to run as copy only Full, set the EnabledCopyOnlyFullAlwaysForAG additional setting. After you set the additional setting, you cannot run differential backups for the Availability group instance. Hence, it is recommended to remove schedules for differential backups.
Before You Begin
Verify that you have Feature Release 11.21 or a more recent version installed on all the nodes in the Always-On cluster.
From the navigation pane, go to Protect > Databases.
The instances page appears.
Click the SQL Server availability group instance that you want to enable copy-only backups for.
The instance page appears.
On the Configuration tab, in the SQL Availability group replicas section, move the Offload full backup job to secondary replica toggle key to the right.