Setting MaxResourceCacheSize and MaxSessionCacheSize agent parameters for Shared Memory on Linux.

Document ID : KB000050992
Last Modified Date : 14/02/2018
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Description:

Could you tell us what Linux system parameters are related to - MaxResourceCacheSize MaxSessionCacheSize agent parameters?

We want to make sure we have the right system settings on our Linux OS's.

Solution:

The MaxResourceCacheSize and MaxSessionCacheSize ACO parameters are related to semaphores and Shared Memory.

On Linux the recommended minimum values for semaphore/shared memory
settings for kernel 2.6 (as well as 2.4 if and where it differs) are:

Kernel 2.6

Use "sysctl kernel.sem" to see actual value of SEMMSL, SEMMNS, SEMOPM, SEMMNI respectively.

Reuse SEMOPM and SEMMSL and modify SEMMNI and SEMMNS as (to modify SEMMSL, SEMMNS, SEMOPM, SEMMNI respectively.)
sysctl -w kernel.sem="250 32000 32 128"

SEMMNU is set internally as SEMMNI.

set shmax:
sysctl -w kernel.shmmax = 2147483648

shmseg is internally set to shmmni and you can set this with:
sysctl -w kernel.shmmni=24 (this is set to 4096 on sles9).