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raid suggestions

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  • User profile image
    The Dealman


    I am a tech for a small organization and we are web server is running windows 2003 web server edition. The server has 6-9.1gb hard drives which is on software raid so what i did was setup a mirror drive for the drive that has the os on it and setup a raid 5 for the other drives.

    The thing is i have 4 18.2 hard drives and i plan to replace the main hard drive and the mirror so when it's time to do this how should i go about doing it?

    I also plan to replace 2 of the 9.1 hard drives that is in the raid with 2 of the 18.2 gig drives, will i run into any problems with this?

    The last thing is i notice that there is 50% overhead on the mirror drives and 25% overhead on the raid 5 drives. Is bad?

    How will that overhead affect server proformace?

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    You're using software RAID on a server?  Oy.  Hope it doesn't see a lot of traffic, software RAID is slooooow.  Consider buying a RAID card.

    If you take a 9.1 GB drive out of an array - or a mirror - and replace it with an 18.2 GB drive, you will only be able to use half of the 18.2 GB drive.  I think you'll have to involve another box, or back up the server to tape, set up the arrays how you like them, and restore from tape.  Dangerous.

    From an overhead point of view... half the drives in a mirror are used for error-checking, so the capacity of a mirror-set is half the sum of the drives.  In a RAID 5, one drive's worth of capacity is used for error-checking, spread out over all of the drives.  So the capacity of a RAID 5-set is one drive less than the sum of all the drives.

    For both mirror and RAID 5... if your drives are different sizes, then the mirror/RAID-set behaves as if all the drives were the size of the smallest drive in the mirror/set, and the extra space is not used, even for error checking

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    The Dealman

    ok thanks Maurits i will look into buy a raid controller. I have one on my sql 2000 server and it's configured pretty good, I might do the same configuration on my web server which is a raid 1  for the os = 2 drives and put all the others in a raid 5. What do you think of this configration for a web server?

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    Steven J Ackerman

    We use an Adaptec SCSI Raid controller on our Win2K server, configured in a RAID 0,1. We have (5) 18.2G Seagate Ultra2 SCSI drives with (4) in the array, and (1) as a hot spare.

    In the ~five years that it's been operational, we've lost two drives but no data.  And its fast.

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