# Best Practices for Application-Aware Backups for Microsoft SQL Server

## Transaction Log Backups Skipped for Simple Recovery Model Databases

If you configure application-aware backups for a SQL Server database that uses the simple recovery model, transaction log backups are skipped. As a workaround, you can use one of the following options:

- Reconfigure the database to use the full recovery model.

- Perform a full backup to ensure that the database is fully protected.

## Backup Preference Configuration for AlwaysON

- Set the primary replica as the backup preference so that there are complete backup cycles available for restores. This configuration option eliminates the following errors:

  - `Skipping database [AlwaysOn_DataBase]. Not a preferred replica to run backup.`

    The software displays this error when the replica is not set as the backup preference and the SQL Server Agent is set to recognize the backup preference setting of the availability groups. When the software attempts a backup operation of the replica, the databases that are part of the availability group are skipped.

  - `Skipping database [AlwaysOn_DataBase]. Only BACKUP LOG is fully supported on secondary replicas. BACKUP DATABASE supports only copy-only full backups of the database, files, or file groups. Differential backups are not supported on secondary replicas.`

    The software displays this error because the secondary replicas support copy-only database backups. When the software attempts to back up databases that are a part of availability group on the secondary replica, the databases are not backed up.

- If transaction log backups are running on all replicas, and truncation occurs during the backup on a secondary replica, the LSN chain on the secondary replica breaks. This action cause the software to automatically attempt to convert the next transaction log backup to a full backup, which is not supported on secondary replicas.

- On new installations, during the initial VSA Appaware configuration, the SQL package is pushed to the guest VM. When the SQL installation is finished the software automatically creates a SQL availability group client and skips backup of the availability group databases, since the VSA AppAware feature does not support availability groups. Since the VSA AppAware feature does not support availability groups, Commvault recommends that you disable auto-discovery by setting the EnableAGDiscovery additional setting on the Commserve database to a value 0.

  - To the CommServe computer, add the EnableAGDiscovery additional setting as shown in the following table.

    For instructions about adding an additional setting from the CommCell Console, see Adding an Additional Setting from the CommCell Console.

    Property | Value
    --- | ---
    Name | EnableAGDiscovery
    Category | CommServDB.GxGlobalParam
    Type | Integer
    Value | 0

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