How to perform parallel and concurrent recoveries
You can recover data by using serial, concurrent, or parallel restore operations. If BRMS performed your saves as serial or concurrent backups, BRMS can restore them either serially or concurrently. However, you can perform parallel restore operations only if BRMS used a parallel operation to perform the save. Both concurrent and parallel restore operations require multiple tape drives.
- Serial Recovery
- This straightforward recovery method is the simplest way to recover data that was saved by multiple control groups. In a serial recovery operation, BRMS issues one recovery job at a time to one tape drive. BRMS performs serial restores in a sequential manner, by restoring one tape and one control group after another. By default, BRMS considers every save and restore a serial operation unless otherwise specified by you.
- Concurrent Recovery
- In a concurrent recovery operation, you send multiple recovery jobs to multiple tape drives to process at the same time (concurrently). You, not BRMS, set up the concurrent recovery. To do this, try to evenly balance the size of the jobs so that they end at the same time. Concurrent recovery operations can reduce your downtime after a system failure by allowing you to recover multiple libraries or objects at the same time.
- Parallel Recovery
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BRMS will restore a saved item sequentially. However, if the item was saved by using parallel save/restore (spreading a single object across multiple media files), BRMS will use the number of resources that you specify up to the number of resources that were used to save the item. A saved item cannot be restored by using parallel recovery if the object was not saved by using parallel.
To perform a parallel restore of a saved item from fewer resources that were used for the save, a media library is recommended because of the additional media mounts that may be required.