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  1. #1
    Join Date
    May 2001
    Posts
    1

    Angry Unanswered: RAID 0+1 and OFA

    I am just moving a database from a AIX machine to a Compaq Proliant 8000 NT(2000) server. There are 10 separate 18 gig drives. I told our NT administrator that I would like a minimum of 5 mirrored drives to spread the datafiles across.

    They just came back to me and have it configured the following way - 1 18gig C: drive, 1 34 gig D: drive and 1 34 gig E: drive, and two hot swappable spare drives

    His logic is that because there is only 3 scsi controller channels, treating them as three logical drives is the best way, as the contention will be on the channels more than the spindles themselves. I tend to disagree, am I right here? I still say that it should be 5 separate drives. This is our biggest and heaviest use database, and I want it done right the first time.

    He says that it is a 0+1 RAID setup (mirrored + striping)

  2. #2
    Join Date
    May 2001
    Posts
    1
    Originally posted by Glen
    I am just moving a database from a AIX machine to a Compaq Proliant 8000 NT(2000) server. There are 10 separate 18 gig drives. I told our NT administrator that I would like a minimum of 5 mirrored drives to spread the datafiles across.

    They just came back to me and have it configured the following way - 1 18gig C: drive, 1 34 gig D: drive and 1 34 gig E: drive, and two hot swappable spare drives
    So you have a single mirror pair on C:, and two-spindle mirrored stripe sets, on D and E ?
    His logic is that because there is only 3 scsi controller channels, treating them as three logical drives is the best way, as the contention will be on the channels more than the spindles themselves. I tend to disagree, am I right here? I still say that it should be 5 separate drives. This is our biggest and heaviest use database, and I want it done right the first time.
    It depends.

    On the SCSI contention issue, you're probably right, unless you have some bizarre mismatch between the performance of your SCSI controllers and your disks. A modern 40MB/s + SCSI controller should comfortably handle four disks for a database I/O access pattern (i.e. it might have trouble if all disks are just linearly streaming data, but not if they have to stop and seek reasonably often).

    Before you decide how to allocate your storage, you should work out what your I/O requirements are, and where you want online redo logs and archive logs. It may be that you have a single table that's heavily used enough to justify a stripe-set, I don't know. You have to analyse your application to decide where to reduce disk contention, and where to increase throughput.

  3. #3
    Join Date
    Jun 2001
    Location
    Drenthe, The Netherlands
    Posts
    1
    Hello,

    When OFA means Oracle Financial Analyzer based on the Oracle Express Server technology it won't use redo logs. It could however be worth to put the database extension files on seperate disk.

    Gerard van Seventer

  4. #4
    Join Date
    Apr 2001
    Location
    Netherlands
    Posts
    191
    I think the OFA he meant is the Oracle File Architecture (Ehmm.. was that what this stands for .. have to look it up :-) )

    This is an Oracle standard of directory and file naming. It describes in which mountpoints / directories the different database files and software products should / could be installed.
    Ruud Schilders
    -----------------
    Oracle DBA
    e-mail : ruud@schilders.it
    URL : www.schilders.it
    Twitter : www.twitter.com/ruudschilders

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