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  1. #1
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    Unanswered: How can I find the RAID stripe size in my system?

    Hi All,
    I am working with db2 v7.2 aix 5.2 , my question is how can I find out the "strip size" in my environment, is there any command or ....

    Thank you inadvance for your help.

  2. #2
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    You need to ask your AIX system administrator.
    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
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    Quote Originally Posted by Marcus_A
    You need to ask your AIX system administrator.
    They told me 32k , but I want to know myself , I know there is a unix command that will show us the strip size, anybody knows?

  4. #4
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    It depends on what kind of disk subsystem you are talking about and whether it is controller by AIX or some other means (like EMC disks). If it driectly attached disk, then the LVM (Logical Volume Manager) can be used. Here is a redbook on the LVM:
    http://www.redbooks.ibm.com/redbooks/pdfs/sg245432.pdf

    32K or 64K are typical for RAID stripe size. Keep in mind that the DB2 entent is in pages so an extent size of 32 is really 128K if you are using 4K pages. So even if the stripe size is 64K, then an extent size of 16 will be a multiple (1X) of the stripe size.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  5. #5
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    Quote Originally Posted by Marcus_A
    It depends on what kind of disk subsystem you are talking about and whether it is controller by AIX or some other means (like EMC disks). If it driectly attached disk, then the LVM (Logical Volume Manager) can be used. Here is a redbook on the LVM:
    http://www.redbooks.ibm.com/redbooks/pdfs/sg245432.pdf

    32K or 64K are typical for RAID stripe size. Keep in mind that the DB2 entent is in pages so an extent size of 32 is really 128K if you are using 4K pages. So even if the stripe size is 64K, then an extent size of 16 will be a multiple (1X) of the stripe size.
    Thank you very much Marcus.

  6. #6
    Join Date
    Aug 2004
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    138
    We use EMC disks. This is the info i have

    EMC Symmetrix RAID 10 (0+1, striped, mirrored) stripe = 960K

    What is dependent on stripe size:
    Extentsize = n(RAID stripe size)
    Prefetchsize = ndisks aka RAID parallel devices(RAID stripe size)
    Prefetchsize = ncontainers(Extentsize)
    Buffersize = n(Extentsize) + 1

    DB2SET registry variable DB2_STRIPED_CONTAINERS=ON to ensure extent boundaries are aligned in the TS

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