This procedure describes how to configure the ONCONFIG file, one of a number of files required for ON-Archive with the Informix database. This file contains essential information required by ON-Archive to correctly perform data recovery (that is, archive, backup, and restore). To see how the ONCONFIG file relates to the other files required by ON-Archive , see Configuration Files for ON-Archive.

Follow this procedure before you start performing archives, backups, and restores of your database.

1. Log on as user informix using the following command:

su - informix

2. Open the ONCONFIG file, which you can normally find in the $INFORMIXDIR/etc directory. The full name of the ONCONFIG file is normally onconfig.<hostname>.<sid> .
3. Set the parameters LTAPEDEV and TAPEDEV .

Although ON-Archive does not actually use LTAPEDEV and TAPEDEV to specify devices, you must enter some value other than /dev/null if you want to be able to restore your system up to the point of failure, for example:

LTAPEDEV /dev/rmt/0hc
TAPEDEV /dev/rmt/1hc



Do not use /dev/null for LTAPEDEV or TAPEDEV if you want to perform a restore of your system up to the time of failure. If you specify the value /dev/null , the logical-log files are automatically marked as backed-up when they become full, effectively discarding logical log information.

4. Set the parameter ALARMPROGRAM .

This parameter specifies the path to the script logevent.sh required to automatically back up your logical log. If you intend to use this script (recommended by SAP), set the parameter as follows:

ALARMPROGRAM /informix/<SID>/etc/logevent.sh

5. Set the parameter LBU_PRESERVE (also known as the "Log Backup High Water Mark" parameter).

To avoid having to do an emergency backup of the logical logs, you must set this parameter. It specifies how many logical-log files the Informix server always preserves (that is, it does not write logging data to these files). SAP recommends you set it as follows:

LBU_PRESERVE 1

In this case, when the second to last logical-log file has filled up, the Informix server effectively stops processing, allowing you to back up the full logical-log files to allow processing to continue. Therefore, no emergency backup is necessary.



Two of the parameters mentioned above – that is, ALARMPROGRAM and LBU_PRESERVE – are necessary in effective logical log management. They help prevent you from having to perform an Emergency Logical-Log Backup.

For a summary of measures you can take to avoid this problem, see Preventing Emergency Logical-Log Backup.

If LBU_PRESERVE is incorrectly set, an alert is raised in the Release 4 alert monitor in the Computing Center Management System (CCMS) of the SAP System. For more information, see Monitoring the Database with the Release 4 Alert Monitor (Informix).

6. When you have finished editing ONCONFIG , you need to stop and restart both the SAP System and the Informix server for the changes to take effect.

You have now completed one of the steps required to configure ON-Archive for performing archives, backups, and restores of your database.

Configuration of ON-Archive

Editing the oper_deflt.arc File for ON-Archive

Editing the config.arc File for ON-Archive

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