WebSphere® MQ uses semaphores and shared
memory. It is possible, therefore, that the default kernel configuration is
not adequate.
Before installation, review the machine's configuration and increase the
values if necessary. The minimum recommended values of the kernel parameters
are given in Figure 1. These
values might need to be increased if you obtain any First Failure Support
Technology™ (FFST™)
records.
Note: - If you intend to run a high number of concurrent connections to WebSphere MQ,
we recommend that you increase the number of kernel timers, or CALLOUTS as
they are known. You configure the number of CALLOUTs available using the NCALLOUT
kernel parameter. By default, NCALLOUT is equal to (16 + NPROC), where NPROC
is the total number of processes allowed on the system. As WebSphere MQ
is threaded, you could choose a value similar to (16 + NKTHREAD). However,
there is an overhead in kernel memory for every CALLOUT defined, so tune this
value to the requirements of the individual system.
- Semaphore and swap usage does not vary significantly with message rate
or message persistence.
- WebSphere MQ
queue managers are generally independent of each other. Therefore system
kernel parameters, for example shmmni, semmni, semmns,
and semmnu need to allow for the number of queue managers
in the system.
See the HP-UX documentation for information about changing these
values.
Figure 1. Minimum recommended kernel parameter values shmmax 536870912
shmseg 1024
shmmni 1024
shmem 1
sema 1
semaem 16384
semvmx 32767
semmns 16384
semmni 1024 (semmni < semmns)
semmap 1026 (semmni +2)
semmnu 16384
semume 256
msgmni 50
msgtql 256
msgmap 258 (msgtql +2)
msgmax 4096
msgmnb 65535
msgssz 8
msgseg 1024
maxusers 32
max_thread_proc 66
maxfiles 10000
nfile 10000
Note: The kernel parameters msgmap, msgmax and msgmnb are
only needed if you are using linear logging. If you are using linear logging,
you also need to set 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.
You must restart the system once you have made any changes to the kernel
parameters.
System Resource Limits
Set the system resource limit
for data segment and stack segment to unlimited using the following commands
in a command prompt:
unlimit -d unlimited
unlimit -s unlimited