Choosing availability options
Availability options are complements to a good save strategy, not replacements. Availability options can significantly reduce the time that it takes you to recover after a failure. In some cases, availability options can prevent you from performing a recovery.
To justify the cost of using availability options, you need to understand
the following items:
- The value that your system provides.
- The cost of a scheduled or an unscheduled outage.
- The type of your availability requirements.
The following list shows the availability options that you can use to complement
your save strategy:
- Journal management enables you to recover the changes to objects that have occurred since your last complete save.
- Access path protection enables you to recreate the order in which records in a database file are processed.
- Disk pools limit the amount of data you need to recover to the data in the disk pool with the failed unit.
- Device parity protection enables you to reconstruct the data that is lost; the system can continue to run while the data is being reconstructed.
- Mirrored protection helps you keep your data available because you have two copies of the data on two separate disk units.
- Clustering enables you to maintain some or all data on two systems. The secondary system can take over critical application programs if the primary system fails.