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Assistance Tuning Buffers

Hi Guys,

I would appreciate your assistance/recommendations with Buffer Tuning

Im experiencing high swapping on Several Buffer as shown Below

Which considerations would you take for adjusting these buffers to optimal Values?

Do you estimate the parameters values by incrementing by 10-20% ? Or is there a better way to determine the best values.

Thanks a lot for your help.

Nametab -->Table Definition

Efficiency HITRATIO % 97

HITS 119.405.209

REQUESTS 123.408.979

DB access quality % 97

DB access 4.006.836

DB access saved 119.399.849

Reorgs 0

Size Allocated KB 9.800

Available KB 8.219

Used KB 8.219

Free KB 0

Free KB 0

Directory entries Available 28.826

Used 28.826

Free 0

Swaps Objects swapped 1.032.168

Frames swapped 0

Resets Total 0

Table definition buffer TTAB

rsdb/ntab/entrycount 28826 Max. number of table definitions buffered

Nametab-->Field Definition

Efficiency HITRATIO % 100

HITS 80.761.920

REQUESTS 81.137.309

DB access quality % 100

DB access 363.063

DB access saved 80.761.378

Reorgs 0

Size Allocated KB 45.515

Available KB 43.263

Used KB 40.109

Free KB 3.154

Directory entries Available 28.826

Used 7.176

Free 21.650

Swaps Objects swapped 355.332

Frames swapped 0

Resets Total 0

rsdb/ntab/ftabsize 43263 kB Size of field description buffer


Efficiency HITRATIO % 100

HITS 385.544.192

REQUESTS 385.922.653

DB access quality % 100

DB access 653.940

DB access saved 565.109.488

Reorgs 0

Size Allocated KB 400.000

Available KB 370.780

Used KB 369.428

Free KB 1.352

Gaps KB 1.303

Directory entries Available 100.000

Used 10.385

Free 89.615

Swaps Objects swapped 206.098

Frames swapped 0

Resets Total 0

Program buffer PXA

abap/buffersize 400000 kB Size of program buffer

abap/pxa shared Program buffer mode


Efficiency HITRATIO % 81

HITS 13.737.920

REQUESTS 16.906.841

DB access quality % 100

DB access 0

DB access saved 0

Reorgs 0

Size Allocated KB 4.096

Available KB 3.375

Used KB 2.757

Free KB 253

Directory entries Available 2.000

Used 1.031

Free 969

Swaps Objects swapped 32.476

  • Frames swapped 428.617*

Resets Total 0

Export/import buffer EIBUF

rsdb/obj/buffersize 4096 kB Size of export/import buffer

rsdb/obj/max_objects 2000 Max. number of objects in the buffer

rsdb/obj/large_object_size 8192 Bytes Estimation for the size of the largest object

rsdb/obj/mutex_n 0 Number of mutexes in Export/Import buffer

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2 Answers

  • Best Answer
    Posted on Dec 15, 2011 at 03:25 PM


    What's your current free physical memory?

    If you have extra free memory, you can allocate 30% to reduce to the swap. Pay attention either the swap happen on size or object directory. Also, you can increase your abap/buffersize to 80000.

    As SAP rule of thumb, total memory usage shouldn't exceed 20% of physical memory for paging.

    for eg: if your system has 10GB, paging used shouldn't exceed 2GB.


    Nicholas Chang

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    • Hi Martin,

      Since 20GB set to MSSQL DB, you can reserve 3GB for system application, process, backup, external process and etc.

      Therefore, you can allocate 27GB to SAP system.

      You can allocate 22GB to PHYS_MEMSIZE, abap/buffersize to 1000000 and 30% to SAP buffer in ST02 where you noticed alot of SWAP. Also, you can allocate additional space to rdisp/ROLL_SHM and rdisp/PG_SHM if the percentage of "In Memory used" is around or more than 80%.

      You can check based on the history usage in ST02.

      However, try not the exceed the shared memory of 27GB for total memory assigned for SAP system, you can check at ST02 -> detailed analysis -> storage.


      Nicholas Chang

  • author's profile photo Former Member
    Former Member
    Posted on Dec 15, 2011 at 03:26 PM


    If you don't find any specific Notes for e.g. Note 373986 - Overflow of the export/import buffer and Note 121808 - Swaps in program buffer although space is free, then better to go with 10-20% increment.


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