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Procedure documentation Choosing Levels and Frequency of Database Backup (ON-Bar)  Locate the document in its SAP Library structure

Use

There are the following levels for Informix database backup (that is, whole-system and storage-space backups) for ON-Bar available with the Informix database server:

Level

Description

0 (full)

Backs up used pages. The most secure but biggest and longest database backup.

1

Backs up all changes since the last level-0 database backup

2

Backs up all changes since the last level-1 database backup

Database backups at levels 1 or 2 are known as "incremental."

Caution

Be very careful when using level-1 or level-2 database backups because they depend on the previous level-0 database backup. If the last level-0 database backup is lost or unreadable, existing level-1 or level-2 database backups 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.

Procedure

  1. If possible, perform a level-0 database backup every day. In the event of failure involving data loss, you can restore the last level-0 database backup and then apply the logs backed up during the day of failure.
  2. Be sure to have enough media capacity (for example, tapes and tape drives) to perform unattended full database backups. If this is possible, it becomes much easier to perform frequent full (level-0) database backups with large databases, since you do not need to continually mount new storage media.
  3. Use full (level-0) database backups unless the database is so large that incremental (level-1 and level-2) database backups are really necessary. Remember that an incremental database backup is no use on its own. It can only be used with an earlier full database backup.

Result

You have decided on the levels and frequency of database backup. This is an essential part of your database backup approach. Therefore, you can be more sure that, in the event of failure involving data loss, you have a suitable backup that you can use to quickly restore the database with minimal data loss.

 

See also:

Informix documentation at http://www.informix.com