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 change these.

It is very important that:

·         The database runs in ARCHIVELOG mode

·         Automatic archiving is enabled

After correct installation of 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<DBSID>.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 archiving 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):

OS> <SAPDATA_HOME>/oraarch/<ORACLE_SID>arch

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

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

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

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

Procedure

...

       1.      Make sure that:

Ў        The archive directory (under UNIX: oraarch) exists.

Ў        The directory is not write-protected.

Ў        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”).

For more information on the BR*Tools commands mentioned below, see Altering the Database Instance with BR*Tools and -f dbalter.

       2.      Check the archiving status of the database by choosing Instance Management ® Show instance status in BR*Tools.

The system displays database instance details.

       3.      Check that:

Ў        Archivelog mode is set to ARCHIVELOG

Ў        Archiver status is set to STARTED

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

                            a.      Do one of the following:

§         Choose Instance Management ® Alter database instance in BRGUI or BRTOOLS and choose the action Set archivelog mode.

§         Enter the command brspace –f dbalter –a archlog from the command line.

§         Enter the following commands in the Oracle tool SQLPLUS:

SQL> connect / as sysdba
SQL> startup mount
SQL> alter database archivelog;
SQL> alter database open;
SQL> archive log list

BRSPACE or SQLPLUS reconfigures the database to set ARCHIVELOG mode on.

                            b.      Repeat steps 2 and 3 to check that ARCHIVELOG has been set correctly.

       5.      If you need to enable automatic archiving (that is, to start the ARCH process), do the following:

                            a.      Enter the following commands in the Oracle tool SQLPLUS:

SQL> connect / as sysdba

SQL> alter system archive log start;

SQL> archive log list

                            b.      Repeat steps 2 and 3 to check that ARCHIVELOG has been set correctly.