Kernel configuration

WebSphere® MQ makes use of System V IPC resources, in particular shared memory and semaphores. The default configuration of these resources, supplied with your installation, is probably adequate for WebSphere MQ but if you have a large number of queues or connected applications, you might need to increase this configuration.

If you are using linear logging, increase msgmnb to 65535 and msgtql to the maximum number of log files that may be used on the system, this is the number of primary and secondary logs added together for all queue managers.

The amount of System V IPC resources available may be determined by looking at the contents of the following files:
  /proc/sys/kernel/shmmax - The maximum size of a shared memory segment.
  /proc/sys/kernel/shmmni - The maximum number of shared memory segments.
  /proc/sys/kernel/shmall - The maximum amount of shared memory
                              that may be allocated.
  /proc/sys/kernel/sem    - The maximum number and size of semaphore sets
                              that may be allocated.
  /proc/sys/kernel/msgmnb - The maximum number of bytes on a message queue.
For example, to view the maximum size of a shared memory segment that can be created enter:
  cat /proc/sys/kernel/shmmax
To change the maximum size of a shared memory segment to 256 MB enter:
  echo 268435456 > /proc/sys/kernel/shmmax

To configure these values every time the machine is restarted we recommend that you add these commands to a startup script in /etc/rc.d/...