ES/SHM_PROC_SEG_COUNT on AIX 5.3 / AIX 6.1

[Former Member]

Hello all,

I'm in the process of re assessing / adjusting our current memory parameters for a kernel 640 system, so if any of you has in depth experience with "SAP Memory Tuning" on AIX systems, please feel free to comment.

These are our current settings:

ES/SHM_MAX_PRIV_SEGS 63

ES/SHM_PROC_SEG_COUNT 64

ES/SHM_SEG_COUNT 4096

ES/SHM_SEG_SIZE 2048

ES/SHM_SEGS_VERSION 2

ES/SHM_USER_COUNT 4096

ES/TABLE SHM_SEGS

I'm considering to change

ES/SHM_MAX_PRIV_SEGS to 15

ES/SHM_PROC_SEG_COUNT to 16

ES/SHM_SEG_COUNT to 8192

SAP Note 789477 recommends the 15 / 16 setting for NW 7.0. Since we will migrate the system in the near future to ERP 6.04 anyway, I think it to be ok to set these parameters accordingly.

What I'm interested in is your knowledge of the ES/SHM_PROC_SEG_COUNT parameter.

Does this mean, that right now with this parameter set to 64 every single WP allocates 64 SHM segments, no mather "how much" Extended Memory the WP actually requires?

Does this also mean, that memory consumption is essentialy higher than it would be, if ES/SHM_PROC_SEG_COUNT were set to recommended value of 16.

Thanks a lot for your advice.

Best Rgs

Thorsten

PS: I know about SAP notes 1048686, 856848, 973227

Edited by: Thorsten Henrici on Jul 21, 2011 6:01 PM

[Former Member]

Hello,

Some additional memory information for your review:

ES/TABLE = SHM_SEGS (switches to the alternative implementation of Extended Memory (EM) as per 789477.

EM/TOTAL_SIZE_MB is used, not em/initial_size_MB when 789477 is implemented.

Parameter Default Meaning

ES/SHM_PROC_SEG_COUNT 65 Specifies the number of shared memory segments that are used as shared and privately.

ES/SHM_MAX_PRIV_SEGS 64 Specifies the number of shared memory segments that are used privately.

This parameter must be lower than es/shm_proc_seg_count.

Also see 973227 - AIX Virtual Memory Management: Tuning Recommendation

Check that the ulimits are configured as per recommended in SAP note 323816.

Also check you memory settings with SAP note 78498.

Regards.

[Former Member]

Hello Kenneth,

thanks for you input.

What I'd like to know is what the consquences of setting ES/SHM_PROC_SEG_COUNT to a specific value are (in detail).

One of the things I'm curious about is, will setting ES/SHM_PROC_SEG_COUNT to a value of 16 generally result in higher memory consumption on the OS level as opposed to setting it to 8 for example. What guideliness should be followed for setting this value.

Best Rgs,

Thorsten