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Raid Array

  • December 30, 2010 at 8:40 am

    #244823

    Please exuse me if this sounds like a basic question but I am new to this...

    I was reading about storage system sizing and determining the number of disks you should use. My question is lets say you have a db requring 1200rps and 400wps...assuiming 125 IOPS we would be running our system on 16 disks running RAID 10. Now lets say 2 years go by and your recalculate your needs to be 25 disks on RAID 10.

    1. Can you just hot swap/add 9 new disks?

    2. If you did add 9 new disks how would you resize/spread out your exisiting data to utilize those new disks? Or would the new disks only be utilized by new data to come?

  • December 30, 2010 at 1:31 pm

    #1267938

    First question answer is it depends. Do you use hardware based RAID or software based RAID? If your server uses its Array controller most likely you have a hardware RAID. It means that if its RAID 1+0 or RAID 5, you could hot swap or add disks to the RAID set. That is the whole point of having RAID, to have redundancy and flexibility.

    Second Question, if you're adding new disk to an existing RAID, it should be seamless because you are not changing how the disks presented to the server. To the server, it'll still be looking at the same disks.

    This is based on my knowledge of how RAID works. Please double check and do more research to verify the info especially if this going to affect your production server.

    Thanks,

    Harry Chandra

  • December 30, 2010 at 1:36 pm

    #1267940

    I tend to agree with Harry. You need to check how your hardware supports the additon.

    For R5, it starts to add in the data and rebalance across all disks, which is a load.

    With R10, it could add a new mirrored pair and then begin to add data on the pair. Not sure how existing data might be rebalanced.

    Note that your hardware might require similar sized disks, might not. Check on that for R10

  • December 30, 2010 at 1:37 pm

    #1267941

    Thanks. I am not planning any changes to any production systems, it was just a thought that I wanted the answer to.

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