How long do I need to keep archive logs

Use the information in this section to help you plan your backup strategy.

You specify how long archive logs are kept in days , using the ARCRETN parameter in USING CSQ6ARVP or the SET SYSTEM command. After this period the data sets can be deleted by z/OS®.

You can manually delete archive log data sets when they are no longer needed.

The queue manager might need the archive logs for recovery.
The queue manager can only keep the most recent 1000 archives in the BSDS, When the archive logs are not in the BSDS they cannot be used for recovery, and are only of use for audit, analysis, or replay type purposes.
You might want to keep the archive logs so that you can extract information from the logs. For example, extracting messages from the log, and reviewing which user ID put or got the message.

The BSDS contains information on logs and other recovery information. This data set is a fixed size. When the number of archive logs reaches the value of MAXARCH in CSQ6LOGP, or when the BSDS fills up, the oldest archive log information is overwritten.

There are utilities to remove archive log entries from the BSDS, but in general, the BSDS wraps and overlays the oldest archive log record.

When is an archive log needed

You need to back up your page sets regularly. The frequency of backups determines which archive logs are needed in the event of losing a page set.

You need to back up your CF structures regularly. The frequency of backups determines which archive logs are needed in the event of losing data in the CF structure.

The archive log might be needed for recovery. The following information explains when the archive log might be needed, where there are problems with different IBM® MQ resources.

Loss of Page set 0

You must recover your system from your backup and restart the queue manager.

You need the logs from when the backup was taken, plus up to three active logs.

Loss of any other page set

You must recover your system from your backup and restart the queue manager.

You need the logs from when the backup was taken, plus up to three active logs.

All LPARS lose connectivity to a structure, or the structure is unavailable

Use the RECOVER CFSTRUCT command to read from the last CF backup on the logs.

If you have been doing frequent backups of the CF, the data should be in active logs.

You should not need archive logs.

Administration structure rebuild

If you need to rebuild the administration structure, the information is read from the last checkpoint of the log for each queue manager.

If a queue manager is not active, another queue manager reads the log.

You should not need archive logs.

Loss of an SMDS data set

If you lose an SMDS data set, or the data set gets corrupted, the data set becomes unusable and the status for it is set to FAILED. The CF structure is unchanged.

In order to restore the SMDS data set, you need to:

Redefine the SMDS data set, and
Fail and then recover the CF structure.
Issuing the RECOVER CFSTRUCT command twice achieves this process.

Issuing the command the first time sets the structure state to failed; issuing the command a second time does the actual recovery.
Note: All non persistent messages on the CF structure will be lost; all persistent messages will be restored.

You will need the logs from the time the BACKUP CFSTRUCT command was issued, so this might require archive logs.

If all LPARs lose connectivity to the structure, the structure is re-created, possibly in an alternative CF. Note that your structure CFRM PREFLIST attribute must contain multiple CFs.

Note: All non persistent messages will be lost; all persistent messages will be re-created by:

Reading the log for the last CF backup
Reading the logs from all queue managers that have used the structure, and
Merging updates since the backup

You require the logs from all queue managers that have accessed the structure since the last backup (back to the time when the backup was taken) plus the structure backup itself in the log of the queue manager that took the backup.

BSDS

Do you need single or dual BSDS?: If you are using dual active logs you should use dual BSDS.
How big does the BSDS need to be?: The BSDS does not need to be very large, and a primary and secondary of one cylinder should be sufficient.