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  1. #1
    Join Date
    Jan 2003
    Posts
    1,605

    Unanswered: Performance question: RAID-5 and DB2_PARALLEL_IO setting

    Hi,

    On DB2 Magazine I have found some tip about setting DB2_PARALLEL_IO environment variable if RAID-5 are used. My system is Intel box, Windows XP, DB2 v7.2 fp5 and data are stored to Enterprise Storage Server (RAID-5 system).

    Question: Will DB2_PARALLEL_IO=* setting reduce I/O operations and so improve performance? Any experience?

    Thanks,
    Grofaty
    Last edited by grofaty; 02-17-04 at 09:44.

  2. #2
    Join Date
    Nov 2002
    Location
    Delaware
    Posts
    186

    Re: Performance question: RAID-5 and DB2_PARALLEL_IO setting

    This is one of those parm you will need to test/test and test some more. On some of our boxes, most data wharehousing, it helped performace, on our oltp systems it hurt performace.
    David Quigley

  3. #3
    Join Date
    Mar 2003
    Posts
    343
    On the datawarehouse, was the improvement in performance quantifiable?

    The reason I ask is we were asked to set it OFF on a DW. And from all that I've read, it should help. However we were on 1+0. If we move to 7+p, I would like to explore options.

  4. #4
    Join Date
    Nov 2002
    Location
    Delaware
    Posts
    186
    We saw about a 10% improvement on 1 of them. Others received no improvment or negative improvement. I really feel it has something to do with our hardward, they are all different type of servers. But you will need to test like I said, Our OLTP systems had mixed results with some getting a -25-50% improvement.
    David Quigley

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