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  1. #1
    Join Date
    May 2011
    Posts
    27

    Unanswered: DB2 - How to estimate proper BUFFERPOOL size?

    DB2 9.7. 8GB RAM on server. Currently BP has 500 MB (number of pages*pagesize) Database has issue with increased IOPS. So we think maybe BP should be increased. How to estimate needed size for BP? Is there some recommendation? Maybe I would like to put it on 1GB. What can be negative effect? Is it always greater better for BP?

  2. #2
    Join Date
    Apr 2008
    Location
    Iasi, Romania
    Posts
    561
    Provided Answers: 2
    Take a look at Configuration Advisor.
    Florin Aparaschivei
    DB2 9.7, 10.5 on Windows
    Iasi, Romania

  3. #3
    Join Date
    May 2011
    Posts
    27
    CA also set me 32768 so BP has 1 GB.
    Can I increased it to at least 1.5 GB although CA is not suggesting it?

  4. #4
    Join Date
    Dec 2007
    Location
    Richmond, VA
    Posts
    1,328
    Provided Answers: 5
    what about letting the DB decide? Set it to automatic. I don't, normally, but that's because I have been doing this for about 20 years and already had been tuning databases and buffer pools prior to it becoming available. I have used it on a couple of occasions though and have not had issue with it.

  5. #5
    Join Date
    Jan 2009
    Location
    Zoetermeer, Holland
    Posts
    746
    Quote Originally Posted by cankovicv View Post
    DB2 9.7. 8GB RAM on server. Currently BP has 500 MB
    7,5Gb left.
    Let the O.S. have 2: 5,5 Gb left.
    Let other DB2 components have 1: 4,5 Gb left.....
    Do you have a better destination for that 4,5 Gb? No? There's your answer: additional bufferpool space 4,5 Gb makes a bufferpool of 5G on a 8G machine. Sounds sane to me.

    But (in your case) activating STMM like dav1mo advices might be a better idea. "db2 activating stmm" google knows
    Somewhere between " too small" and " too large" lies the size that is just right.
    - Scott Hayes

  6. #6
    Join Date
    May 2011
    Posts
    27
    thank you guys for your help

  7. #7
    Join Date
    Feb 2014
    Posts
    13
    Use memory tracker to view the allocated memory for all the bufferpools : db2mtrk -d

    More info about bufferpools :
    DB2 Basics: Table spaces and buffer pools

    DB2 Basics: Table spaces and buffer pools

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