Archive Levels and Frequency (ON-Archive and ontape)

Archive Levels and Frequency (ON-Archive and ontape)

There are the following archive levels for ON-Archive and ontape available with the Informix database:

Level	Description
0 (full)	Archives all used pages. The most secure but biggest and longest archive
1	Archives all changes since the last level-0 archive
2	Archives all changes since the last level-1 archive

Archives at levels 1 or 2 are known as "incremental".

Be very careful when using level-1 or level-2 archives because they depend on the previous level-0 archive. If the last level-0 archive is lost or unreadable, existing level-1 or level-2 archives are useless if the database needs to be restored. For more information about how to check that your data is readable for a restore, see Data Consistency with SAPDBA.

The best archive strategy is to perform a level-0 database archive every day. In the event of a system failure, you can restore your last level-0 archive and then apply the logs backed up during the day of failure.

SAP recommends that you:

Have enough tape drive capacity to perform unattended full database archives. If this is possible, it becomes much easier to perform frequent full (level-0) database archives with large databases, since you do not need to continually mount new tapes.

Only perform full (level-0) archives unless the database is so large that incremental (level-1 and level-2) archives are really necessary. Remember that an incremental archive is no use on its own. It can only be used with an earlier full archive.