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  1. #1
    Join Date
    Dec 2004
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    54

    Unanswered: Tablespace containers

    I have a DMS tablespace with size of 5 GB, here which is advisable way whether a single container of 5GB or more than one container?

  2. #2
    Join Date
    May 2003
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    USA
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    IF you have an OLTP database with a decent size bufferpool, then it probably does not matter.

    If you have a decision support database (frequent table scans) then it will definitely help if you have multiple containers, but each container should be on a different disk or array.

    If you have multiple containers, then your prefetch size should be a "multiple" of your extent size and the "multiple" should be equal to the number of containers in the tablespace. Also, set the following on:

    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
    Aug 2001
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    4,650
    It also depends on the storage system you use ... If you use one of the 'modern' disk arrays, if your filesystem is spread across multiple underlying disks, then having multiple containers is not of any use ... In this case, remember to set DB2_STRIPED_CONTAINERS to ON ...

    But if you are using an inbuilt disk, say, you 5Gigs will perform better with multiple containers, especially for DSS as Markus mentions ...

    The reason to have multiple containers is to read more than one extent at a time, with each extent sitting on different disks, ie, they can be read simaltaneously without having an impact on one another ... Yes, in this context, remember, PREFETCHSIZE of the tablespace and NUM_IOSERVERS also play a critical role in your I/O design

    HTH

    Sathyaram
    Visit the new-look IDUG Website , register to gain access to the excellent content.

  4. #4
    Join Date
    Aug 2001
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    UK
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    ooops ... I meant Marcus and not Markus ...

    Markus is the IDUG Insider Webmaster

    Cheers
    Sathyaram
    Visit the new-look IDUG Website , register to gain access to the excellent content.

  5. #5
    Join Date
    May 2003
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    USA
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    I believe that in DB2 version 8 DB2_STRIPED_CONTAINERS is set to ON by default on any new tablespaces created. It is only a concern if you upgrade from version 7.
    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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