Setting Up Archiving (SAP Library - SAP Database Guide: Oracle (BC-DB-ORA-DBA))

Setting Up Archiving

Use

This procedure tells you how to check the archiving parameters and ARCHIVELOG mode for your Oracle database and, if necessary, how to reset these. It is very important that:

The database runs in ARCHIVELOG mode
Automatic archival is enabled

After correct installation for an SAP System, the Oracle database meets both these criteria. In this case, the online redo log files are automatically archived when full (that is, following a redo log switch). This is important because it allows the online redo log files to be reused for fresh archive data, so that archiving of the log files can continue at all times.

Prerequisites

The following parameters in the init.ora file control the archiving process for the Oracle database:

Parameter	Note
log_archive_start = true	Preset by SAP
log_archive_dest = <directory>/<file prefix>	Part of the file name
log_archive_format = <Oracle default>	Use the Oracle default

log_archive_start = true causes the background archive process ARCH to be started automatically when the database is started. This means that automatic archival mode is enabled.

log_archive_dest defines the archive directory of the online redo log files for archiving. It is delivered with the specification of the following SAP standard path (this example is for a single instance installation on UNIX):

BS> <SAPDATA_HOME>/saparch/<ORACLE_SID>arch

See SAP Note 316642 for information on how to avoid an "archiver stuck" error by changing the archive directory.

For more information, see Environment Variables (UNIX) and Environment Variables (Windows NT).

Note

The Oracle database names the offline redo log files using the string <ORACLE_SID>arch followed by the log sequence number.

You can back up the offline redo log files with SAPDBA with BRARCHIVE. The offline redo log files are the copies of the online redo log files saved in the archive directory.

Procedure

Make sure that:

The archive directory (under UNIX: saparch) exists.

The directory is not write-protected.

The directory has enough free space. Otherwise, the archiving process cannot archive any log files and no further actions are possible on the database (this is known as "Archiver Stuck").

Note

For more information on the SAPDBA commands mentioned below, see Setting Archive and Database Mode with SAPDBA.

Check ARCHIVELOG mode by choosing Archive Mode in SAPDBA.

The system displays archiving details. Database log mode should be set to archivelog.

If you need to reset ARCHIVELOG mode, do this in either of the following ways:

Choose Archive mode ® Toggle database log mode in SAPDBA.

SAPDBA shuts down the database, configures the database mode, and restarts the database.

Enter the following commands in the Oracle tool SQLPLUS:

SQLPLUS> connect internal
SQLPLUS> startup mount
SQLPLUS> alter database archivelog;
SQLPLUS> alter database open;
SQLPLUS> archive log list

SQLPLUS starts the database in ARCHIVELOG mode.

Repeat the previous step to check that ARCHIVELOG has indeed been set correctly.

Check whether AUTOMATIC ARCHIVAL is enabled by choosing Archive Mode in SAPDBA.

The system displays archiving details. Automatic Archival should be set to enabled.

If you need to enable AUTOMATIC ARCHIVAL (that is, to start the ARCH process), do this in either of the following ways:

Choose Archive mode ® Toggle automatic archival in SAPDBA.

SAPDBA enables automatic archival by starting the ARCH process.

Enter the following commands in the Oracle tool SQLPLUS:

SQLPLUS> connect internal

SQLPLUS> alter system archive log start;

SQLPLUS> archive log list

Repeat the previous step to check that AUTOMATIC ARCHIVAL has indeed been enabled.