Why Raw disks in OPS ?
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Thread: Why Raw disks in OPS ?

  1. #1
    Join Date
    Sep 2002
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    376

    Why Raw disks in OPS ?

    Hi,

    What is the reason for having Raw disks for parallel server ?

    Is there any specific reason behind this ?

  2. #2
    Join Date
    Aug 2002
    Location
    Atlanta
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    block contention, excessive pinging yadda yadd yadda.

    OPS can almost be considered beta for rac. The overhead associated with OPS is so high that Oracle insists that you use RAW devices to help reduce that overhead.

    In 9i we allow clustered file systems and the RAC code has been rewritten to be appreciably more effiecent than in OPS through the
    marvelous cache fusion.

    steve
    I'm stmontgo and I approve of this message

  3. #3
    Join Date
    Dec 2000
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    Ljubljana, Slovenia
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    Well, AFAIK it's not because of "block contention, excessive pinging yadda yadd yadda and other owerhead". It's simply because the underlying OS don't allow simultaneous access to same filesystem devices from differen nodes. It's not because of Oracle, it's because of the OS. And it's all because of proper locking mechanism - at OS level, not at database level.

    In 9i, clustered file system was introduced to overcome this, but it is still entirely implemented at OS level. Database is only something that's sitting on top of that.

    And BTW, there is at least one operating system (at least the one that I'm aware of) that doesn't require RAW devices fo Oracle Parallel Server, for any release of Oracle OPS form Oracle7 upward! So this proves that OPS doesn't require RAW devices by its design - it can function as efficiently on ordinar file system if only the underlying OS allow it.
    Jurij Modic
    ASCII a stupid question, get a stupid ANSI
    24 hours in a day .... 24 beer in a case .... coincidence?

  4. #4
    Join Date
    Sep 2002
    Posts
    376
    thanx jurij

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