How It Works
To perform instant recovery, Veeam Explorer for Microsoft SQL Server uses the Veeam Explorers Recovery Service that runs in the background. This removes the necessity to keep Veeam Explorer running during an entire instant recovery session. Once you have started an instant recovery session, you can close Veeam Explorer and then launch it later when necessary.
When you start an instant recovery session in Veeam Explorer for Microsoft SQL Server, the following happens:
- Veeam Explorer uses backup files to start two iSCSI mount sessions in parallel:
- The first mount is used to publish the database on the target production server and attach it to the target SQL Server instance.
- The second mount is used to copy database files to the target server in the background.
- While the published database is online, all changes in database files that occur after publishing are saved in cache on the mount server.
- After all database files are copied to the target server, Veeam Explorer uses the cache to synchronize changes in database files.
- After the synchronization, you can switch over to the up-to-date copy of the database on the production server. Depending on the option you choose, the switchover starts manually, automatically according to a specified schedule or immediately after synchronization. During switchover, Veeam Explorer does the following:
- Stops the published database.
- Uses the cache to synchronize differences between the published database and the copied database files.
- Drops the published database.
- Starts the recovered database.
Instant recovery session is resilient to network disruption, backup server or mount server crash. If anything disrupts the restore process, the restore process stays in the waiting mode and performs 10 automatic retries every 5 minutes. If the retries fail, you can launch retry after the server or network is up.