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  1. #1
    Join Date
    Jan 2003

    Unanswered: Concurrent I/O on AIX and DB2 64 bits

    hi Guys,

    Since we upgraded our db2 instance to 64 bits and enable CIO/DIO in all the Database filesystems noticed that we are having some performance degradation. Even more the Database backups that use to take only 2 hours is now taking between 5 and 6 hours. In our environment we are running AIX 5.4 and db2 fixpack 12 64 bits. Also this database is only 150 gigs. Thanks for any help.



  2. #2
    Join Date
    Jan 2007
    Jena, Germany
    Are you writing the backup images to the file systems that have direct I/O enabled?

    Also, do you actually have the hardware for CIO? There is not a really compelling point to do concurrent I/O if you have just a single disk, I would say.
    Knut Stolze
    IBM DB2 Analytics Accelerator
    IBM Germany Research & Development

  3. #3
    Join Date
    Sep 2003
    concurrent I/O takes data directly from disk to buffer pool(not disk to filecache and the from filecache to bufferpool); gives you the functionality of raw file space with the convenience of cooked file systems; if you use tivoli, make sure the api64 dsm.sys has same parameters as the api(32) dsm. sys; util_heap-size is where backup is formatted; make sure it is increased; you can reduce the filecache minperm%=2 maxperm%= 30 and increase all db buffer pools and heap sizes

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