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  1. #1
    Join Date
    Mar 2004
    Posts
    84

    Unanswered: Oracle on San vs Local drives? single drive vs multiple drives

    Hi Experts,
    Quick question based on your experience.
    I have a Oracle DB, where the dmp file is about 3 GB.
    I want to reorganize the DB system and want to know the expert opinion before I go ahead.
    1) Would it be more advatagious if the data files are located on SAN or on local harddrives? The reason why we have it currently on SAN is for Disaster Recovery.
    2) Would it be advantagious to have multiple SAN mount points like D, E, F, G with 50GB each and distribute the datafiles accross them vs having all the datafiles on one single mount point with 100 GB space?
    Thanks for your input.
    Kishore

  2. #2
    Join Date
    Jun 2004
    Location
    Liverpool, NY USA
    Posts
    2,509
    A sans acts like one giant disk drive that can have chunks allocated out. You will not gain any speed advantages by having one volume or 50. All access to the sans goes through the same nic or fiber channel, no matter how the sans storage is carved up.

    If it helps, we currently are using a 36 processor sun box going to a 4 terabyte sans and our response is great.
    Bill
    You do not need a parachute to skydive. You only need a parachute to skydive twice.

  3. #3
    Join Date
    Dec 2002
    Posts
    1,245
    Quote Originally Posted by beilstwh
    A sans acts like one giant disk drive that can have chunks allocated out. You will not gain any speed advantages by having one volume or 50. All access to the sans goes through the same nic or fiber channel, no matter how the sans storage is carved up.
    I would like to respectfully disagree with your statement; with the following caveats:

    1. If the disks on the SAN are carved into multiple physical arrays; and

    2. If you're network fabric is not already saturated; and

    3. If you can isolate IO by type (random read/write versus sequential write)

    Then you should indeed be able to garner additional performance by isolating files onto separate physical devices.

    As pointed out, it will not do you any good to carve up the same physical array into multiple volumes -- you must separate the IO onto distinct physical drives. Ideally, you would want to isolate log files (sequential writes) onto RAID 1 (or better RAID 10) devices. Data files would go on RAID 5 (or RAID 10 if you can afford it).

    We did this in our environment for a couple of vended (3rd party) database applications and the performance improvement was quite substantial and noticeable to the end user. It certainly helps to have multiple HBAs installed on the server and to have a combination of operating system/HBA driver/data path management utility that permits full optimization of dual data paths (ie, reading over one channel while writing over the other).

    Regards,

    hmscott
    Have you hugged your backup today?

  4. #4
    Join Date
    Mar 2004
    Posts
    84
    Quote Originally Posted by hmscott
    I would like to respectfully disagree with your statement; with the following caveats:

    1. If the disks on the SAN are carved into multiple physical arrays; and

    2. If you're network fabric is not already saturated; and

    3. If you can isolate IO by type (random read/write versus sequential write)

    Then you should indeed be able to garner additional performance by isolating files onto separate physical devices.

    As pointed out, it will not do you any good to carve up the same physical array into multiple volumes -- you must separate the IO onto distinct physical drives. Ideally, you would want to isolate log files (sequential writes) onto RAID 1 (or better RAID 10) devices. Data files would go on RAID 5 (or RAID 10 if you can afford it).

    We did this in our environment for a couple of vended (3rd party) database applications and the performance improvement was quite substantial and noticeable to the end user. It certainly helps to have multiple HBAs installed on the server and to have a combination of operating system/HBA driver/data path management utility that permits full optimization of dual data paths (ie, reading over one channel while writing over the other).

    Regards,

    hmscott
    Thanks Guys for the input.
    hmscott, This is exactly what I am going to do after I had the discussion with our network admin. our SAN is an array and matrix of 50GB each and I am going to have him mount each volume as a disk.
    Kishore

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