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  1. #1
    Join Date
    Sep 2002

    Unanswered: How to determine the NUM_IOSERVERS

    We are using DB2 V8.2 ESE on AIX (64-bits) and would like to know how to
    determine the values for the NUM_IOSERVERS. According to DB2 manual or
    technotes, they stated that it is advised to set the NUM_IOSERVERS equal to
    the number of physical disks that the database resides on plus 1 or 2.

    In my case, it is a SAN environment (ESS), so a ESS logical disk appear to
    AIX as a physical disk, but in fact are logical storage allocated across
    multiple physical disks in an ESS array.

    So, under this kind of environment, when I set the NUM_IOSERVERS, should I
    still count the number of disks appear on the AIX level or how many physical disks on the ESS array?

  2. #2
    Join Date
    May 2003
    If you are using a disk subsystem that has striped arrays (regardless of exact type of stripping) then I would recommend setting NUM_IOSERVERS to the number of CPU's.

    For high-end SAN or NAS systems, I would also issue the following dbm command for the instance:
    db2set DB2_PARALLEL_IO=*
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  3. #3
    Join Date
    Mar 2003
    let's say there are 8 dbps per host and 8 cpu's on a host. As wongpcl mentioned, the Aix "disks' are striped across 8 SAN disks. What would you recommend in this case for a v8.1 system?

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