Quick question about RAID and backing up large drives

Discussion in 'Buying Tips and Advice' started by livingfortoday, Sep 13, 2006.

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To RAID or not to RAID?

  1. Do it - you'll have it all backed up anyways!

    4 vote(s)
    57.1%
  2. Don't do it - you'll lose everything and be very sad.

    3 vote(s)
    42.9%
  1. livingfortoday macrumors 68030

    Joined:
    Nov 17, 2004
    Location:
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    #1
    Just a quick poll. I'm going to be setting up a new file server soon to hold all my media and whatnot, and can't decide on a drive configuration. I'm thinking of running 2 x 300GB drives in RAID 0 so that I can see it as a single 600GB drive. I've heard there is some performance benefit to this, but that if one drive fails I lose everything. My other option is to mount them as two separate drives, and while that's safer for me, it's kind of a pain to have to access two volumes instead of one. Well, for me anyways. But I'm lazy like that.

    Oh, and I guess I should ask - what's the best way to backup such large amounts of data? I have those two 300GB drives right now, and a 200GB one I use for backup of my most vital files. I'd like to be able to securely back it all up on a semiregular basis, though (weekly, maybe?). Any suggestions?
     
  2. sw1tcher macrumors 65816

    sw1tcher

    Joined:
    Jan 6, 2004
    #2
    True, though it is only a slight speed improvement.

    Very true.

    Have you considered getting another pair of drives and setting up a RAID 1+0? That way, you'll get lots of storage space, plus the security of having everything backed up.

    If one drive fails, you won't lose any data. Then just replace that drive immediately.

    If you're looking for a quick and easy way to back up such large amounts of data, you can't beat the price per GB of large HDDs. They're so inexpensive nowadays that you can pick up a 400GB HDD for about $150 (usually after rebate). If the data is really important, I'd also consider a tape drive (an expensive option) or recordable Blu-ray or HD-DVD discs (also expensive).

    I personally use several backup methods (HDDs, DVDs) and store one or two off site in case something were to happen.
     
  3. livingfortoday thread starter macrumors 68030

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    #3
    That is a good idea, the only problem I see is that since I have two 300GB drives, I'd have to get more of that size to do the RAID 1+0. I kinda feel like that's limiting my future expansion, ya know? Not that I could afford two extra drives right now, but my next purchase was hopefully going to be a 500GB or 400GB drive.
     
  4. livingfortoday thread starter macrumors 68030

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  5. livingfortoday thread starter macrumors 68030

    Joined:
    Nov 17, 2004
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    #5
    Ok, one more question, actually, kind of a "is this possible" question.

    If I took the 2 x 300GB disks and combined them with RAID 0, could I then take a 500GB, and, say a 100GB drive and combine them as (I think it's called) JBOD to get a 600GB drive as well... and then mirror the two sets with RAID 1?

    I'm sorry, I don't know much about RAID setups, so I'm trying to make sense of it and find the best way to do this. Thanks for any help!
     
  6. crazzyeddie macrumors 68030

    crazzyeddie

    Joined:
    Dec 7, 2002
    Location:
    Florida, USA
    #6
    Your best bet is to create a mirror RAID. The speed increase won't be giant from a stripe, but the risk will be. Mirror is 100% restorable.
     
  7. cube macrumors G4

    Joined:
    May 10, 2004
  8. tyr2 macrumors 6502a

    tyr2

    Joined:
    May 6, 2006
    Location:
    Leeds, UK
    #8
    What OS are you running on this fileserver? You can certainly do what you suggest with Linux using the 'md' drivers. Not sure if you could achieve this with OSX tho.

    Have you considered RAID5. 3 x 300gb disks would give you 600 usable and redundacy against failure of one of the disks.
     
  9. livingfortoday thread starter macrumors 68030

    Joined:
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    #9
    Well, I was planning on running Tiger, but it only allows RAID 0 and 1 through Disk Utility. Pretty sure I'd have to get a RAID card for RAID 5. I'm not sure I really understand how RAID 5 works, btw. If I could do 3x300 and have 1 300GB drive be backup, that'd be great... but how does it work, exactly?
     
  10. topgunn macrumors 65816

    topgunn

    Joined:
    Nov 5, 2004
    Location:
    Texas
    #10
    RAID 5 works by using a parity bit. For every 2 bits of data, 3 bits get written. An elementary example would be you have one bit with a value of 13 and a second bit with a value of 27. The parity bit would be a total of the two thus it would have a value of 40. The first bit gets written to the first drive, the second bit to the second drive and the third to the third. If you were to lose a hard drive you could derive the missing information. For example, if you lost drive one, you would have ? + 27 = 40. Easy to determine that the 1st bit was 13. Same with the second or third drives (13 + ? = 40 or 13 + 27 = ?). On one RAID type (5), the parity bit is stripped across the drives along with the data. On another RAID type (4), you have a dedicated parity drive. 4 is not used much at all.

    With RAID 5, you get a speed increase and redundancy. You can't get both from either RAID 1 or 0. The more drives you add, the faster it gets. If you need added security, you can add a spare to the array thus allowing you to lose two hard drives before the RAID dies.
     
  11. livingfortoday thread starter macrumors 68030

    Joined:
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    #11
    Wow, ok, thanks! That makes a lot of sense now. Yeah, RAID 5 definitely seems like something I'd want to do, then, only I don't think I can do it in OS X with the tools the OS has built in. Are there software solutions to do this, or would I have to get a RAID card to implement RAID 5?

    Edit: Also, would the 3 300GB drives have to be blank at the start when I set up this RAID, or any RAID for that matter? 'Cause if so, I'd have to find somewhere to put all the stuff that's on there now...
     

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