IBM MQ logging parameters for Linux, UNIX, and Windows
You can update IBM® MQ logging parameters to tune the performance of MQ.
You specify queue manager parameters in the qm.ini file on Linux® and UNIX operating systems. On Windows systems, you set these parameters by using the Log page of the queue manager properties notebook that can be accessed from the MQ Services snap-in, or within the log stanza in the registry.
On distributed platforms, the following parameters affect the performance of MQ:
- LogType
- Specify linear logging rather than the default of circular logging
to ensure that no log data is lost, and that in the event of a system
failure all messages can be recovered and replicated. You will need
to monitor the disks where archive logs are stored to ensure that
they do not become full, however.
When linear logging is configured, a message is entered in the queue manager error log to show which log files can be deleted. The MS0L SupportPac also provides a Java-based utility for maintaining linear log files on UNIX or Windows operating systems.
- LogBufferPages
- Specify the largest possible value for the amount of memory that is allocated to buffer records for log writes. The maximum number of 4 KB buffer pages is 512. Larger buffers lead to higher throughput, especially for larger messages. If you specify 0 (the default), the queue manager selects the size.
- LogFilePages
- This parameter specifies the size of each primary and secondary log file in units of 4K pages. This parameter controls how much data can be written to a log file before another file is used. Increasing this value can improve message throughput by reducing the amount of switching between log files, and can also speed the task of log archiving. A value between 4096 pages and the maximum of 16,384 pages (16 MB and 64 MB) is recommended. You specify a value when you create the queue manager and cannot change the value.
- LogPrimaryFiles
- If you expect large transactions or long-running batch jobs without interim commits, increase the number of primary log files from the default of 3 to accommodate your workload.
- LogSecondaryFiles
- Typically, you should allocate two secondary log files for every three primary log files.
- LogWriteIntegrity
- Set the method that is used to write log records (SingleWrite, DoubleWrite, TripleWrite) based on your business needs. The default of TripleWrite might have a small extra performance cost but ensures complete integrity of the log records in case of a disaster recovery scenario. If the disk where your logs are stored has a battery-backed cache, then you can set this parameter to SingleWrite.