Snapshot Database Recovery

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Snapshot Database Recovery

You can now recover a database backup that was captured and restored by a third‑party snapshot tool; for example, VMWare or Amazon Elastic Block Store (EBS) snapshots.

For details about external third‑party snapshot backups, see "Non-JADE Backups" in the Developing a Backup Strategy White Paper.

The third‑party tools are responsible for detecting any errors that were raised during the movement of data. A restored snapshot is considered to be database data exactly as it was copied when the snapshot was created. No JADE backup or restore verification checks can be performed.

A roll‑forward recovery must be performed to establish database integrity.

A snapshot recovery requires the snapshot processing to happen after the snap begin call, completes before the snap end call, and all journals generated between these two points are required to restore file‑level integrity.

When performing a snapshot recovery:

If a database is accidentally shut down during snapshot processing, do not restart it until the snapshot processing is complete. When restarted, the database will perform a snapshot recovery.
Ensure that changing the access mode to DB_SNAPSHOT occurs before snapshot processing begins.
Ensure that snapshot processing completes before restoring access mode to DB_DEFAULT.

The pMode parameter of the jomChangeAccessMode Application Programming Interface (API) call, documented in Chapter 3 of the JADE Object Manager Guide, now has the DB_SNAPSHOT, DB_ARCHIVE, and DB_DEFAULT mode constants, which conditions the database for external snapshot backup, quiesces the database for archive backup, and restores the database to initial mode and usage values, respectively.

The JadeDatabaseAdmin class now provides the Mode_Exclusive constant (which requests exclusive access to the database) and the Mode_Snapshot constant, which can be specified in the mode parameter of the changeDbAccessMode method to condition the database for external snapshot backup.

The jdbadmin program enables you to specify StartSnapshot and EndSnapshot database actions, to condition the database for recovery from a non‑JADE backup and to take the database out of snapshot mode, respectively. (For details, see "StartSnapshot" and "EndSnapshot", respectively, in Chapter 2 of the JADE Database Administration Guide.)