Reorganizing in NOARCHIVELOG Mode (SAP Library - SAP Database Guide: Oracle (BC-DB-ORA-DBA))

Reorganizing in NOARCHIVELOG Mode

Use

This procedure tells you how to reorganize the Oracle database with SAPDBA in NOARCHIVELOG mode.

Note

If you use the export/import reorganization method, a large number of redo log files are written. However, if you deactivate the ARCHIVELOG mode, there is no significant acceleration of the reorganization.

The archive process ARCH runs parallel to the remaining background database processes, which means that the CPU load is not significantly greater in ARCHIVELOG mode. Therefore, the reorganization is not significantly slowed down.

Prerequisites

Consider the following when deciding whether to run the reorganization in ARCHIVELOG or NOARCHIVELOG mode:

NOARCHIVELOG mode has the following advantages:

You can safeguard against the risk of an archive stuck.

You save space in the archiving directory of the offline redo log files, <SAPDATA_HOME>/saparch .

BRARCHIVE does not have to run for the period of the reorganization, as no offline redo log files are created.

Time can be saved in the event of a recovery, because you can resume from the backup performed immediately after the reorganization.

We only recommend deactivating ARCHIVELOG mode under certain conditions, since it interrupts the continuity of the redo log files. Once the reorganization is complete, you must reactivate the ARCHIVELOG mode and perform a complete offline backup of the database. Remember that online backups are only secure after a complete offline backup of the database.

Consider using NOARCHIVELOG mode when reorganizing special tablespaces.

Procedure

For maximum security, perform an online or offline backup of the entire database.

A complete backup of the database is not required if all redo logs since the last backup are available. If this is the case, it is sufficient for security purposes to use the Oracle command ALTER SYSTEM SWITCH LOGFILE to force switching of the redo log file. This means that the online redo log files, which were not yet backed up by ARCH (this normally only concerns the current online redo log group), can also be backed up to the archiving directory.

Shut down the database using SAPDBA.

Deactivate ARCHIVELOG mode using SAPDBA.

Perform the reorganization.

After the reorganization, you must immediately reactivate ARCHIVELOG mode using SAPDBA.

For maximum security, perform a complete offline backup of the database immediately.

If you try to recover the database with an old backup, this would only be possible to the state before the reorganization (remember that the reorganization was not performed in ARCHIVELOG mode).

Although an online backup is possible, it is risky if every data file was not backed up. If the database crashes before the online backup is complete, a recovery can only proceed to the state before the reorganization (starting from the last backup before the start of the reorganization). All changes made to the database during the online backup would be lost and would have to be repeated manually after the reorganization.