WebSphere MQ Linux system settings

WebSphere MQ Linux system settings needs to be setup before starting the Installation process. These are basically additional settings that has to be done Linux machines for setting the hard and soft limit values. These values are very essential in terms of Message Queue processing.

Following information is taken from the new link of Knowledge center for Message Queue. Link for reference here,

http://www.ibm.com/support/knowledgecenter/en/SSFKSJ_7.5.0/com.ibm.mq.ins.doc/q008550_.htm

1. Kernel configuration

2. Maximum open files

3. Maximum processes

1. Kernel configuration

The minimum configuration for WebSphere MQ for these resources is as follows:

kernel.shmmni = 4096
kernel.shmall = 2097152
kernel.shmmax = 268435456
kernel.sem = 500 256000 250 1024
fs.file-max = 524288
kernel.pid-max = 120000
kernel.threads-max = 48000

To view the kernel parameters for your system, enter the following commands:
cat /proc/sys/kernel/shmmni
cat /proc/sys/kernel/shmall
cat /proc/sys/kernel/shmmax
cat /proc/sys/kernel/sem
cat /proc/sys/fs/file-max

To load these sysctl values immediately, enter the following command: sysctl -p
If you do not issue the sysctl -p command, the new values are loaded when the system is rebooted.

2. Maximum open files
If the system is heavily loaded, you might need to increase the maximum possible number of open files. If your distribution supports the proc file system you can query the current limit by issuing the following command:

cat /proc/sys/fs/file-max

To report on the current maximum, and in-use, number of file descriptors for your system, enter the following commands:
/sbin/sysctl fs.file-max
/sbin/sysctl fs.file-nr

For a standard WebSphere MQ queue manager, set the nofile value for the mqm user to 10240 or more. To set the maximum number of open file descriptors for processes running under the mqm user, add the following information to the /etc/security/limits.conf file:
mqm              hard    nofile          10240
mqm              soft    nofile          10240

Use command, ulimit -n to check the values that are configured for open files.

3. Maximum processes

A running WebSphere MQ queue manager consists of a number of thread programs. Each connected application increases the number of threads running in the queue manager processes. It is normal for an operating system to limit the maximum number of processes that a user runs. The limit prevents operating system failures due to an individual user or subsystem creating too many processes. You must ensure that the maximum number of processes that the mqm user is allowed to run is sufficient. The number of processes must include the number of channels and applications that connect to the queue manager.
The following calculation is useful when determining the number of processes for the mqm user:
maximum processes = 2048 + maximum WebSphere MQ connections  + maximum WebSphere MQ channels

You can configure the maximum number of processes for the mqm user as follows:
mqm             hard    nproc           4096
mqm             soft    nproc           4096