Which of the following descriptions about the snapshot backup of the OceanStor backup solution is...

The snapshot function of the backup software can automatically discover the storage volume where the database and mail system are located, and initiate a quiescing of the application before the snapshot.

To trigger a hardware storage snapshot. The volume where the file system is located cannot be automatically discovered and needs to be configured separately.

After the snapshot is completed, you can choose to catalog and index the snapshot data (to ensure application-level recovery or small particle recovery).

Offline backup of snapshots. The backup adopts offline mode and does not occupy the resources of the production system.

After adopting snapshot backup, data can be recovered from the recovery layer and protection layer. The compliance layer has a special purpose and cannot be used for data recovery.