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How is data stored on disk?

  • April 8, 2004 at 4:31 pm

    #179167

    Hi all, I have a question about SQL 2000 running on Win 2000.  If we have four 73G drives mapped as one drive (D, and lets say that I create a table and import 100 million rows into this table...does the data get spread across all four drives or does Windows start writing the data to drive 1 until its full and then write to drive 2, and so on?

    Thanks for your help.

  • April 8, 2004 at 4:37 pm

    #502230

    How are they combined? Windows can do it either way.

  • April 8, 2004 at 4:46 pm

    #502233

    Hi Steve,

    They are combined to be one drive to Windows.  As far as windows is conncerned, its drive D:  In what instances does the data get stored across all 4 drives and in what instances it doesn't?   Thanks again.

  • April 8, 2004 at 5:23 pm

    #502235

    Sorry, are they a volume set or a striped set? In a volume set, I believe things are written one drive at a time until it is full. However, if you lose a drive, you lose everything.

    In a stripe set, everything is written to all drives at once. If you lose a drive you lose everything. If you stripe w/ parity, you can lose 1 drive.

  • April 8, 2004 at 5:42 pm

    #502238

    Thank you very much Steve.  So, if I understand you correctly, on RAID 5 (which is what we have), then the data is spread across all drives?

  • April 8, 2004 at 6:36 pm

    #502239

    Correct shahgols, RAID 5 is Stripe set with parity.  In other words, all of the data is written across all the drives and you could loose one drive and not loose your data.


    - JH

  • April 8, 2004 at 7:17 pm

    #502241

    Thank you everyone, that is the exact info I needed! 

  • April 9, 2004 at 6:25 pm

    #502359

    There is a good explantion of different raid levels at

    http://www.acnc.com/04_01_05.html

     


    Michael R. Schmidt
    Developer

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