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  1. #1
    Join Date
    Oct 2010
    Posts
    56

    Unanswered: Catalogcache_sz ,maxappls

    Hi ,I have db2 v8.2 , installed on AIX 5.3 .
    db cfg parameter MAXAPPLS configured on AUTOMATIC,
    db cfg parameter CATALOGCACHE_SZ configured on MAXAPPLS*4

    I'm asking if this configuration is recommended ,
    and how can I tune the catalog cache hit ratio ?

    Tks,

  2. #2
    Join Date
    Oct 2004
    Location
    DELHI INDIA
    Posts
    338
    if there is no catalogcache overflow, then your current configuration should be fine. If there is overflow, then keep on increasing the configuration value until there is very minimal overflow. Moreover, the catalog cache hit ratio should be high enough , say > 85-90% to ensure that sufficient amount of memory is available.

    Keep on taking DB Snapshot during the peak transaction volume to get a more representative figures for all of the above.

    Jayanta Datta
    DB2 UDB DBA
    IBM India, Global Delivery
    New Delhi

  3. #3
    Join Date
    Jun 2003
    Location
    Toronto, Canada
    Posts
    5,516
    Provided Answers: 1
    Quote Originally Posted by JAYANTA_DATTA View Post
    the catalog cache hit ratio should be high enough , say > 85-90%
    How would you calculate the catalog cache hit ratio?

  4. #4
    Join Date
    Oct 2004
    Location
    DELHI INDIA
    Posts
    338
    100 - ( Catalog cache inserts * 100 / Catalog cache lookups )

    Jayanta Datta
    DB2 UDB DBA
    IBM India, Global Delivery
    New Delhi

  5. #5
    Join Date
    Apr 2006
    Location
    Belgium
    Posts
    2,514
    Provided Answers: 11
    these are health_indicators. where did you find the values for these elements ?
    Best Regards, Guy Przytula
    Database Software Consultant
    Good DBAs are not formed in a week or a month. They are created little by little, day by day. Protracted and patient effort is needed to develop good DBAs.
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  6. #6
    Join Date
    Oct 2010
    Posts
    56

    MAXAPPLS configured on AUTOMATIC

    Hi,

    If MAXAPPLS configured on AUTOMATIC and CATALOGCACHE_SZ configured on MAXAPPLS*4, it means that this parameter is actually an automatic also.

    So how to increase this parameter is set automatically? Is there a disability for automatic parameter?

  7. #7
    Join Date
    Oct 2004
    Location
    DELHI INDIA
    Posts
    338
    if you are not getting any error mentioning about you have exceeded limit for maximum applications, then your current setting is fine. In case you give the CFG parameter a hard value e.g. 400 to start with, then you are disabling the automatic parameter.

    Similarly for Catalog cache by default you have values of -1, so if you give it a fix value say 64 4 K page, you are disabling automatic feature for it.

    From the snapshot of Database, you can monitor and find out whether your current value is fine. Moreover for a overflow condition, your diaglog will also be reported with Catalog Cache overflow errors.

    Jayanta Datta
    DB2 UDB DBA
    IBM India, Global Delivery
    New Delhi

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