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 Typical Parameter Settings for SAP BuffersLocate this document in the navigation structure

Repository Buffer (Nametab Buffer)

The following table provides an overview of the capacity of the repository buffer. This capacity is allocated using the corresponding profile parameters. It also specifies the number of the associated key:

Buffer Number of Entries in the Management Area User Data [in Kilobytes] Key

Table definition (TTAB)

rsdb/ntab/entrycount

Non-Unicode: rsdb/ntab/entrycount´ 188 / 1024

Unicode: rsdb/ntab/entrycount´ 292 / 1024

42

Field description (FTAB)

rsdb/ntab/entrycount

rsdb/ntab/ftabsize

43

Short nametab (SNTAB)

rsdb/ntab/entrycount / 4

rsdb/ntab/sntabsize

45

Initial record (IRBD)

rsdb/ntab/entrycount / 4

rsdb/ntab/irbdsize

44

Note

The size of an entry in the management area is - depending on the hardware platform used - around 50 bytes.

All of the listed buffers are in memory pool 40. The size of the shared memory pool is therefore controlled by the parameter ipc/shm_psize_40. For more information, see Repository Buffer

Table Buffers

Generic key (resident) buffer (TABL)

The number of directory entries (one for every resident table or each generic area) is defined with zcsa/db_max_buftab. The size of the data area in bytes is defined by zcsa/table_buffer_area. You can use ipc/shm_psize_19 to control the positioning of the buffer. The parameter is usually set to -10 (Pool 10). The parameter zcsa/exchange_mode should not be changed. Keep the default value Off.

Single key (partial) buffer (TABLP)

The number of directory entries (one for each table) is defined with rtbb/max_tables. The size of the data area in KB is defined by rtbb/buffer_length. You can use the parameter ipc/shm_psize_33 to control the positioning of the buffer. It is normally set to 0, that is, the buffer is not in a pool. The parameter rtbb/frame_length defines the length of a frame in KB and should always be set to the default value of 4. For more information, see Table Buffers.

Program Buffer

You can only define the size of the program buffer with one parameter: abap/buffersize. The size is defined in KB. The number of directory entries is calculated from this parameter. You can control the placing of the buffer with ipc/shm_psize_06. This parameter is normally set to 0, that is, the buffer is not in a pool. For more information, see Program Buffers.

SAP GUI Buffers

Screen buffer (PRES)

You can define the size of the directory, that is, the maximum number of screens (dynpros) using zcsa/bufdir_entries. The total size of the buffer in KB is defined by zcsa/presentation_buffer_area. The storage area for the directory is included here.

Control the placement of the GUI buffers using parameter ipc/shm_psize_14. This parameter is usually set to-10, which means that it is in pool 10.

CUA buffer

The parameter rsdb/cua/buffersize defines the total size of the buffer in KB. The number of directory entries is calculated as total size / 2KB. You can control the placing of the buffer with ipc/shm_psize_47. This parameter is normally set to -40, that is, the buffer is in pool 40. For more information, see SAPgui Buffers.

Roll and Paging Buffers

The parameters rdisp/ROLL_SHM and rdisp/PG_SHM are used to allocate the roll and paging buffer in 8KB blocks.

This buffer is normally placed outside a pool. To place the buffer inside a pool, set the parameters ipc/shm_psize_08 and ipc/shm_psize_09. For more information, see Roll and Paging Buffers

SAP Calendar Buffer

You can define the size of the calendar buffer in bytes in profile parameter zcsa/calendar_area. For more information, see SAP Calendar Buffer

 

See also:

SAP Note 103747 on the SAP Service Marketplace

Special Aspects of Tuning

Access Statistics

Reasons for Bad Buffer Quality

Buffer Types