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Former Member

Swaps in ST02

Hi all,

We just increased the program buffer from 850 MB to 950 MB 3 weeks back and then to 1050 MB a week back.The system looks normal for a few days and then again i can see the swpas increaing.We already have 16 GB of memory on a 64bit Win NT platform.The DB is db2 v 8.1.5......

So should i again increae it. also i read somewhere that increasing too much program buffer area willl lead to buffer fragmentation .

I am not sure . please suggest if it is ok to increase.

Also the Nametab ,Table definition, Short NTAB,Field definition, Initial records buffers are showing a lot of swaps ..

I looked at the relevant parameters:

rsdb/ntab/entrycount = 70000

rsdb/ntab/ftabsize = 62500 KB

rsdb/ntab/sntabsize = 2500 KB

rsdb/ntab/irbdsize = 30 000 KB

Which values should i change...please suggest.....

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3 Answers

  • Best Answer
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    Former Member
    Apr 08, 2008 at 08:45 AM

    Hi Mangesh,

    a swapping Programm buffer is normal!

    But be sure that there are not more than about 10.000 Swaps a Day.

    Regards

    Manuel

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    • Former Member

      Hi,

      The parameters should not be changed frequently,there could be many reasons for swaps.Check your st04 and sto3n what would be the reason,if standard programs or some reports run weekly or something like that then you can not tune them and even not needed,so just check dont just change the parameters.

      Regards,

      Vamshi.

  • Apr 07, 2008 at 03:58 PM

    Hi Mangesh,

    Swaps are not directly related to the value of parameter abap/buffersize only. You have a set of memory management parameters that help you tweak the system in order to reduce as much as possible the swaping...

    Read

    http://help.sap.com/saphelp_nw04/helpdata/en/02/96268c538111d1891b0000e8322f96/frameset.htm

    Regards

    Juan

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    Former Member
    Apr 07, 2008 at 06:28 PM

    Hi,

    Yes, you are correct, increasing the sizes too much it creates adverse effect on buffer quality.

    just because of some swaps you see in ST02, doesn't justify the increase the sizes.

    from the Basis point of view, In a typical Prod. system we can't avoid some swaps with program buffer, but it also depend upon how many?

    Things you need to keep an eye on it is, when you increase the buffer sizes, how is your buffer quality is 100% or less.. 100% is not good, typically it should be around 97-99%.

    And also keep track of transport imports happening in the system, more the changes in the repository, swaps will be more (program buffer).. etc..

    -K

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    • Former Member Former Member

      Hi Desai,

      Swaps occur there is no problem, and as far as i know there is no standard value that can be set if this many no of swaps occur.You just check and tune by using st04 detailed analysis which one is leading to longer time and then tune your buffers accordingly.Dont just keep on changing the buffer size.

      Regards,

      Vamshi.