Basis and others: Note 425207 - SAP memory management, current parameter ranges

Summary

Symptom
It is not clear which maximum values can be assigned to specific parameters in which kernel release for SAP memory management.
Other terms
ztta/roll_extension, abap/heap_area_nondia, abap/heap_area_dia,
abap/heap_area_total, ES/SHM_USER_COUNT, ES/SHM_SEG_COUNT,
ES/SHM_PROC_SEG_COUNT, ES/SHM_MAX_PRIV_SEGS
Solution

Current parameter settings:
                          32-bit               64-bit

Releases lower than 46D:
ztta/roll_extension      <2GB                <2GB

abap/heap_area_total    <2GB                 <2GB
                                0 = unlimited            Remark 5.)
abap/heap_area_(non)dia  <2GB                 <2GB
                                0 = unlimited            Remark 5.)

ES/SHM_SEG_COUNT      R/3 <4000            R/3 8000
                          OS  4096            OS  unlimited
ES/SHM_USER_COUNT      R/3 <4000            R/3 4096   Remark 1.)

Release 46D:
ztta/roll_extension      <2GB                  <4GB    Remark 5.) + 6.)
abap/heap_area_total        64-bit float value
                                0 = unlimited            Remark 5.)
abap/heap_area_(non)dia  <2GB                 <2GB
                                0 = unlimited            Remark 5.)

EM/MAX_SIZE_MB              up to 46D Patch Level 569, Remark 4.)
(linux: em/max_size_MB)
EM/TOTAL_SIZE_MB            as of 46D Patch Level 570, Remark 4.)
ES/SHM_SEG_COUNT        R/3 <4000          R/3 8000,   Remark 3.)
                        OS   4096            OS  unlimited
ES/SHM_USER_COUNT      R/3 <4000          R/3 8000,   Remarks 1.)+ 2.)

ES/SHM_PROC_SEG_COUNT  <=9                <=64        Remark 5.)
ES/SHM_MAX_PRIV_SEGS    <=8                <=63        Remark 5.)

Release 640, 700, and 710:
ztta/roll_extension      <2GB              unlimited
abap/heap_area_total        64-bit float value
                                0 = 1 Terabyte           Remarks 5.)+ 8.)
abap/heap_area_(non)dia  <2GB                 <2GB
                                0 = 1 Terabyte           Remarks 5.)+ 8.)

ES/SHM_SEG_COUNT      R/3 <4000            R/3 32768
                          OS  4096             OS  131000
ES/SHM_USER_COUNT      R/3 <4000          R/3 32768,   Remarks 1.) + 2.)

ES/SHM_PROC_SEG_COUNT  <=9                <=64, due to roll_extension
ES/SHM_MAX_PRIV_SEGS    <=8                <=63, due to roll_extension
                                                            Remark 5.)

EM/TOTAL_SIZE_MB         64 Bit Float Value, max. 0,25 Terabyte

em/global_area_MB        2000                8180        Remark 7.)

Comments:

1. (Status on August 6, 2001) Depends on the size of the Select mask of the dispatcher and the gateway. Both can only contain 2K handles. This means that the maximum number of (GUI and RFC) contexts is limited, as is the maximum number of entries in rdisp/tm_max_no. An entry that makes demands on ES/SHM_USER_COUNT causes at least one entry that makes demands on ES/SHM_SEG_COUNT. This means you must set ES/SHM_SEG_COUNT to be larger than or equal to ES/SHM_USER_COUNT: Hence the extension in Remark 2).

2. (Status on October 24, 2001) Is increased to 8192 in 6.20 in the default and in 46D and 6.10 with patches: Maximum ES/SHM_USER_COUNT = 8192 is valid for the following Patch Level: 46D = 739; 6.10 = 220; 6.20 contained in the default settings. The following applies for older patch level versions of these releases: Maximum ES/SHM_USER_COUNT = 4096

3. As of Patch Level 579.

4. The parameter(s) only apply to Linux (em/max_size_MB) and AIX (EM/MAX_SIZE_MB, but only up to the specified patch level). On these platforms, the maximum size of the extended memory is not limited by em/initial_size_MB. This is important to limit the total memory used, otherwise, in a worst case scenario, the system may run out of swap space and a paging collapse may occur (see Note 517006 for further information). This means that the value of the parameter must be considerably lower than the size of the swap space available.

5. In this context, see Note 548845, which does not allow internal modes that are larger than 2 GB.

7. This applies to 640 as of patch level 167, for kernel 700 and higher it is contained in the standard system.

8. This applies to 640 as of patch level 126, for kernel 700 and higher it is contained in the standard system. The theoretical value is 32000. However, for practical reasons, it cannot be increased. See also Note 785365.

Header Data


Release Status:	Released for Customer
Released on:	04.08.2008 06:07:30
Master Language:	German
Priority:	Recommendations/additional info
Category:	Help for error analysis
Primary Component:	BC-CST-MM Memory Management