Backup window reduction
IBM® i high availability solutions can reduce the time your system or services are unavailable during your backups. The time it takes to complete a backup from start to finish is called a backup window. The challenge is to back up everything in the window of time that you have.
The obvious techniques of reducing or eliminating
the backup window involve either decreasing the time to perform the
backup or decreasing the amount of data backed up. This includes the following:
- Improved tape technologies
- Faster and denser tape technologies can reduce the total backup time.
- Parallel saves
- Using multiple tape devices concurrently can reduce backup time by eliminating or reducing serial processing on a single device.
- Saving to non-removable media
- Saving to media that is faster than removable media, for example directly to direct access storage device (DASD), can reduce the backup window. Data can be migrated to removable media at a later time.
- Data archiving
- Data that is not needed for normal production can be archived and taken offline. It is brought online only when needed, perhaps for month-end or quarter-end processing. The daily backup window is reduced since the archived data is not included.
- Saving only changed objects, daily backups exclude objects that have not changed during the course of the day.
- The backup window can be dramatically reduced if the percentage of unchanged objects is relatively high.
Other save window reduction techniques leverage
a second copy of the data (real or virtual). These techniques include:
- Saving from a second system
- Data resilience technologies, such as logical replication, that make available a second copy of the data can be used to shift the save window from the primary copy to the secondary copy. This technique can eliminate the backup window on the primary system. Therefore, it does not affect production since the backup processing is done on a second system.
- Save while active
- In a single system environment, the data is backed up using save processing while applications may be in production. To ensure the integrity and usability of the data, a checkpoint is achieved that ensures a point-in-time consistency. The object images at the checkpoint are saved, while allowing change operations to continue on the object itself. The saved objects are consistent with respect to one another so that you can restore the application environment to a known state. Save while active may also be deployed on a redundant copy achieved through logical replication. Employing such a technique can enable the save window to be eliminated effectively.
- IBM System Storage® FlashCopy®
- This technology uses the IBM System Storage function of FlashCopy on an independent disk pool basis. A point-in-time snapshot of the independent disk pool is taken on a single System Storage server. The copy of the independent disk pool is done within the System Storage server, and the host is not aware of the copy. Clustering enables bringing the copy on to the backup system for the purpose of doing saves or other offline processing. Clustering also manages bringing the second system back into the cluster in a nondisruptive fashion. Clustering supports multiple independent disk pools from the same system or multiple production systems being attached to the storage unit at the same time.