Configuration for AIX

Prerequisites

For most of the profile parameters the default values are also correct for AIX. Only with a few AIX-specific parameters might you have to change the parameter values.

Note Note

The following recommendations are valid only for the 64 bit platform.

End of the note.

Procedure

Recommended parameters in the instance profile:

Parameter

Recommendations

Meaning

ES/TABLE

SHM_SEGS

Switches to the alternative implementation of the extended memory (EM)

EM/TOTAL_SIZE_MB

262144

(256 GB)

This limts the EM to 256 GB, which on many machines amount to a lifting of the restriction. By decreasing the parameter, the EM can be limited.

The following parameters should only be changed after consulting with SAP.

Parameter	Default	Meaning
`ES/SHM_PROC_SEG_COUNT`	`16`	Specifies the number of shared memory segments that are used as shared and privately.
`ES/SHM_MAX_PRIV_SEGS`	`15`	Specifies the number of shared memory segments that are used privately. Caution This parameter must be lower than `es/shm_proc_seg_count`. End of the caution.
`ES/SHM_MAX_SHARED_SEGS`	`1`	Specifies the number of shared memory segments. The value comes from `ES/SHM_PROC_SEG_COUNT` – `ES/SHM_MAX_PRIV_SEGS`
`ES/SHM_USER_COUNT`	`8192`	The maximum number of users in all open sessions.
`ES/SHM_SEG_COUNT`	`8192`	The maximum number of AIX system segments that ESSHM uses.
`ES/SHM_SEG_SIZE`	`4096` (4GB)	Size of the AIX system segments (in megabytes) Caution Be aware that the operating system parameters also have to allow this segment size. End of the caution.

These recommendations depend not only on whether the alternative method of implementing extended memory is active, but also on the AIX version used.

The following SAP Notes relate to memory management under AIX:

Note Number	Short Text
789477	A lot of extended memory on AIX (64-Bit) as of Kernel 6.20
174882	Not enough shared memory segments in AIX