Restores of availability databases

Depending on how availability databases are backed up, legacy restore and VSS restore operations are available to restore the availability databases on primary or secondary availability replicas.

There are some restrictions with restoring availability databases:

Legacy restore

You can restore an availability database on either a primary or secondary replica.

During the restore process, the restored database is removed from the availability group. When a database is removed from the availability group, the database becomes a local database on that replica. The database is restored as a local database. After this restore is complete, manually add the database back to the availability group. However, before you add the database to the availability group, verify that the data on all replicas is transactionally consistent.

To verify data is transactionally consisent, verify that the backup copy contains data and transaction log records. Full backups and differential backups contain data and transaction log records so that the restored database is transactionally consistent.

After you verify that the data is transactionally consistent, the database can be added to the availability group.

VSS restore

Because of a SQL Server limitation, you cannot restore a VSS backup to an alternative SQL server instance. Therefore, VSS backups must be restored to the same SQL server instance where the snapshot was taken.