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  1. #1
    Join Date
    May 2004

    Question Unanswered: DB2 num_ioservers

    We have an EMC SAN for our 1/2 TB financial database on P/Soft. Having high number of prefetch - I have tried num_ioservers values from 10 - 200 and the results vary little. Have anyone heard of this?
    I am assuming it may be an EMC bottleneck of some kind since the SAN consists of hundreds of physical disks the NUM_IOSERVERS setting may become irrelevant.
    Not sure - just a guess.

    We are running Solaris 8 O/S
    DB2 7.2 fixpack 6

    Last edited by thartson; 05-07-04 at 19:05.

  2. #2
    Join Date
    May 2003
    The bottleneck is probably the number of processors and/or the number of containers per tablespace.

    I usually set it equal to the number of containers that reside on separate physical disks per tablespace. For RAID disks, it would be the number separate arrays in a container. If you only have one container in a tablespace, you will get improved performance from the striped EMC SAN, but I don't think DB2 itself will initiate parallel I/O in that situation (for a single query).

    It definitely helps if you have at least one processor for each I/O server, although this may not be absolutely necessary. If you have enough processors, then you could set it equal to 2x, 3x, etc the number of containers in a tablespace.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

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