Conditions for RAID 1

Posted on 2007-08-01
Last Modified: 2013-11-14
I'm trying to build a new computer with RAID 1 configuration (Mirroring). What are the requirements of the 2 drives that I'll be putting in? Same capacity? Same model? Please advise.
Question by:alateos
    LVL 25

    Expert Comment

    Yes it is better to use a matched pair., make, model and capacity.

    It will work with mixed models and sizes but you limit yourself in both capacity and performance of the smaller/slower disk.  For a new system there is no reason not to do it properly.

    Author Comment

    what if everything is the same except for the model
    LVL 25

    Accepted Solution

    Depends on what the difference between the models is and how much of a difference it really is.  Its a lowest common denominator.  So your older or slower model limits total performance.  That said the differece the two drives could be pretty small in the first place making it a non issue.

    It is really more of a cost issue than technical.  It just does not make sense to buy a good drive to pair with a bad drive if you are buying all new drives.  This becomes more pronounced with high performance drives where the cost difference between drives can be quite large.  With two similar consumer 7,200 rpm SATA drives the cost difference might be $5-10 really not a big deal.  

    If however you were pairing a 10,000 rpm drive with a 7,200 rpm drive (raptor with anything else),  then it really is a waste as the 10,000 rpm drive probably cost $100-150 more and will really not provide any benefit.  So in this case either save the money and get two 7,200 units or go for performance with a pair of 10,000 rpm units.

    A lot of time these days when a drive in an array needs to be replaced it is done with larger drives due to availability or costs having dropped so much.   Eventually all the drives get upgraded and then the array can be enlarged to match the newer capacity.

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