HowTo - Shorten the Backup History for SAP MaxDB

This section should help you to shorten the backup history of SAP MaxDB/liveCache databases.

Symptom

When you use transactions DBACOCKPIT, DB50, LC10, DB14, the Database Studio or Database Manager CLI (DBMCLI) to display the backup history, the system requires a long time for this process or the following or similar errors may occur:  (6: overflow)

Reason and Prerequisites

The backup history of a database that is based on SAP MaxDB (for example, SAP liveCache, SAP Content Server, OneDB and so on) is stored in the files dbm.knl and dbm.mdf in the im run directory (usually, /sapdb/data/wrk/<SID>, SAP MaxDB Log Files 7.9).
These files are always enhanced at the file end so that the files get larger as the number of backup operations or restore operations increases.
Since the files include the information even of backups that are no longer significant (for example, because the backup medium has been overwritten in the backup cycle in the meantime), the backup history contains an increasing amount of insignificant data.

Solution

The solution is described in SAP note 1089402 Reducing the backup history for the SAP MaxDB/liveCache database. Starting with SAP MaxDB 7.9.10.02 the DBM command db_truncatehistory is available to short the backup history (SAP Note 1444241, documentation db_truncatehistory).

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