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  1. #1
    Join Date
    Jul 2003
    Posts
    2,296

    Unanswered: Oracle ASM - LUN sizes?

    I've dealt with various environments with all different types of LUN sizes attached to ASM disk groups. Recently I have one environment with a diskgroup with 3 very large LUNs attached (240G each). I've noticed considerable disk usage (80-100% for all 3 luns) as compared to a few other environments with smaller lun sizes attached to their asm diskgroup. (comparable code and usage for all environments mentioned)

    Does anyone have any opinion on sizing of the raw disks (LUNs) that get associated with the ASM diskgroup?

    Just from my experience and observations it seems the really large LUNs get hit very hard and the db performance suffers as compared to the smaller LUN sizes which perhaps spread out the disk usage more evenly. This is just from observing raw disk utilization from the server side.

    I can't really find a concrete documentation or benchmarks testing this specific theory of mine. I am in the midst of testing it myself but I don't have full control over the environments so it is a long-involved process to convert everything for testing.

    thanks!
    - The_Duck
    you can lead someone to something but they will never learn anything ...

  2. #2
    Join Date
    Aug 2003
    Location
    Where the Surf Meets the Turf @Del Mar, CA
    Posts
    7,776
    Provided Answers: 1
    Some folks advocate Stripe And Mirror Everything (SAME) which is easy to configure & manage.
    With SAME you end up with few but LARGE volumes & have little control over what data resides where.

    An alternative is to make many small RAID-1 volumes which is more challenging to manage & tends to "waste" or under utilize disk space.
    You can lead some folks to knowledge, but you can not make them think.
    The average person thinks he's above average!
    For most folks, they don't know, what they don't know.
    Good judgement comes from experience. Experience comes from bad judgement.

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