For further information on WebSphere MQ tuning, see the article Configuring and tuning WebSphere MQ for performance on Windows and UNIX

Configuration changes adopted in the different environments to obtain performance results

To obtain the performance results, the following changes are required for all the queue managers used in the different environments:

Buffer Sizes

Increase the value of DefaultQBufferSize and DefaultPQBufferSize to 50MB for the input and output queues used in the tests. This is the maximum supported and is used because in most tests, messages of up to 20MB are used. When you use smaller messages all of the time, a smaller value is likely to be more appropriate.

Persistent Messaging

Modify the MQ log parameters to test persistent messages:

  • Set LogBufferPages to 4096
  • Set LogFilePages to 65535
  • Set LogType to circular
  • Set LogPrimaryFiles to 15
  • Set LogSecondaryFiles to 1


Set circular logging for all WebSphere MQ queue managers used in the tests.


Set the following TCP/IP values for the TCP stanza in the queue manager .ini file:

  • SndBuffSize=70000
  • RcvBuffSize=70000
  • RcvSndBuffSize=70000
  • RcvRcvBuffSize=70000
  • Blocking=YES


The WebSphere MQ queue manager log is located on a SAN or RAID disk with a non-volatile fast write cache. Such disks are consistently capable of I/O times of 1 ms compared with a time of 6 ms for a single 10,000 RPM SCSI disk.
When you use a disk with a fast write cache, it is important that it has a non-volatile capability because the log data is critical to the integrity of your queue manager.

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