Configuration for AIX

Prerequisites

For most of the profile parameters the default values are also correct for AIX (see Setting the Profile Parameters (UNIX)). Only with a few AIX-specific parameters might you have to change the parameter values.

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

Procedure

Recommended parameters in the instance profile:

Parameter

Recommendation

Meaning

ES/TABLE

SHM_SEGS

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

EM/TOTAL_SIZE_MB

262144

The default setting as good as cancels the limitation on the extended memory. You can restrict the EM by reducing the parameter value.

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

Parameter

Default

Meaning

ES/SHM_PROC_SEG_COUNT

64

Specifies the number of shared memory segments that are used as shared and privately.

ES/SHM_MAX_PRIV_SEGS

48

Specifies the number of shared memory segments that are used privately.

This parameter must be lower than es/shm_proc_seg_count.

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

Size of the AIX system segments (in megabytes)

Be aware that the operating system parameters also have to allow this segment size.

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

78498

High paging rate on AIX 4.x database servers

143646

AIX patches for new memory management (95454)