Setting the Profile Parameters (UNIX)

Use

The ideal parameter settings depend on the hardware resources available (main memory and swap space) on the one hand and the system load on the other, that is, the maximum/average number of (active) users working on an application server.

Procedure

The following table serves as a guideline for setting profile parameters on UNIX platforms. In most cases the default values are also the values recommended by SAP.

Memory management on IBM AIX is different from on other UNIX systems. For this reason, setting the AIX-specific parameters is dealt with in a separate section (see Configuration for AIX).

Parameter

Unit

Default setting

Comment

abap/heaplimit: Work Process Restart

Bytes

40000000

(40 MB)

ztta/roll_extension: Limit for Extended Memory

Bytes

2000000000

(2 GB)

If there is a large amount of memory available, you can also increase the value if certain programs are taking up lots of memory.

abap/heap_area_dia: Heap Memory Limit for Dialog Work Processes

Bytes

2000000000

(2 GB)

abap/heap_area_nondia: Heap Memory Limit for Non-Dialog Work Processes

Bytes

2000000000

(2 GB)

abap/heap_area_total: Heap Memory Limit

Bytes

2000000000

(2 GB)

You can monitor the physical memory and swap space using transaction ST06.

Allocated virtual memory consists of allocated memory from:

·        All SAP instances

·        Database buffers and database processes

·        Operating system, special file system cache

You can view this using transaction ST02 ® Detail Analysis ® Storage.

em/initial_size_MB: Size of Extended Memory

Megabyte (MB)

2040

(2 GB)

You can increase this value, up to about 4000.

rdisp/ROLL_SHM: Roll Buffer Size

8 KB blocks

16384

(128 MB)

Absolute upper limit: 250000 blocks (2 GB) for special applications (file system must be large enough)

rdisp/ROLL_MAXFS: Maximum Roll File Size

8 KB blocks

2048

(16 MB)

Absolute upper limit: 250000 blocks (2 GB) for special applications (file system must be large enough)

rdisp/PG_SHM: Size of the Paging Buffer

8 KB blocks

8192

Absolute upper limit: 250000 blocks (2 GB) for special applications (file system must be large enough)

rdisp/PG_MAXFS: Maximum Size of SAP Paging File

8 KB blocks

32768

(256 MB)

Absolute upper limit: 250000 blocks (2 GB) for special applications (file system must be large enough)

ztta/roll_first: Size of the Initial Allocation from the Roll Area

Bytes

1

One (1) byte means that only one small amount of memory specifically for that system is allocated and then extended memory is used. A high value (1 MB or more) may be useful if there is not a lot of extended memory available (see Recognizing and Correcting Problems).

ztta/roll_area: Roll Area

Bytes

4 

(4 MB)

em/blocksize_KB: Segment Size for the Extended Memory

Kbyte

4096

(4 MB)

With many small user contexts it can be useful to reduce this value (to about 1024).