Help setting up 2 SSD in a RAID on MBP

Discussion in 'MacBook Pro' started by MrXiro, Nov 27, 2011.

  1. MrXiro macrumors 68040

    MrXiro

    Joined:
    Nov 2, 2007
    Location:
    Los Angeles
    #1
    I've got 2 512GB SSD I am trying to put in a RAID on my MBP with an Optibay in it.

    I'm not sure what RAID configuration I'm supposed to use to get one large 1TB drive... I did a Striped 64k, but I tried copying over my original HDD with only 13gb on it and it's going REALLY slow... so I think I did something wrong. Can't seem to find exact settings for the best speed and performance.

    Anyone have any tips?

    ----------

    Just did some more reading and I think I know what I did wrong. It should be Concatenated Disk Set is what I want not Striped...

    If anyone can confirm for me that would be fantastic. Thanks.
     
  2. sfoalex macrumors 6502

    Joined:
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    Location:
    Earth, no seriously.
    #2
    You want RAID 0, which is a simple striped set. I've never done a RAID in software on the Mac so I don't know how to set that up. I've always shied away from software RAID and stuck to dedicated hardware for that. Sorry I can't help in that regard.

    I chimed in more out of concern then to assist you in creating the set. I'm not sure you're going to see any performance boost considering the controller is likely the bottleneck in the first place. Not to mention you are taking an awful risk by striping the drives in software. Any glitch and you face data corruption across the stripe.

    I'd advice against this. I'd just use them independently.
     
  3. MrXiro thread starter macrumors 68040

    MrXiro

    Joined:
    Nov 2, 2007
    Location:
    Los Angeles
    #3
    Thanks, I appreciate the advice... but actually this project isn't for me but for my buddy and he wanted it as one big drive. I think the Concatenation type is the way I should do it... it's basically just sandwiching the 2 SSDs into one giant one and writing everything linearly... is that right?

    Here's what I found from http://www.cuddletech.com/veritas/raidtheory/x31.html:

    "2.1. RAID Type: Concatenation

    Concatenations are also know as "Simple" RAIDs. A Concatenation is a collection of disks that are "welded" together. Data in a concatenation is layed across the disks in a linear fashion from on disk to the next. So if we've got 3 9G (gig) disks that are made into a Simple RAID, we'll end up with a single 27G virtual disk (volume). When you write data to the disk you'll write to the first disk, and you'll keep writing your data to the first disk until it's full, then you'll start writing to the second disk, and so on. All this is done by the Volume Manager, which is "keeper of the RAID". Concatenation is the cornerstone of RAID.

    Now, do you see the problem with this type of RAID? Because we're writing data linearly across the disks, if we only have 7G of data on our RAID we're only using the first disk! The 2 other disks are just sitting there bored and useless. This sucks. We got the big disk we wanted, but it's not any better than a normal disk drive you can buy off the shelves in terms of performance. There has got to be a better way.........."
     
  4. sfoalex macrumors 6502

    Joined:
    Aug 11, 2001
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    #4
    I think you truly want RAID 0. You get the sum value of the combo, and the speed combo of both. However, you're doing the RAID in software and the controller is likely already the bottleneck. So I'm frankly doubting you see any performance advantage. All I see is increased risk for no reason at all.

    Sorry, I just can't advise you do this. If you wish to do it anyway, then RAID 0 is what you are looking for. Sometimes it is called "a simple stripe". Why not let others chime in as well. And perhaps forward the comments to your friend. I just hate to see him do this. I think he'll regret it. Honestly.
     
  5. MrXiro thread starter macrumors 68040

    MrXiro

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    Los Angeles
    #5
    I just convinced him based one what you said. We'll just keep them separate. Thanks.
     
  6. sfoalex macrumors 6502

    Joined:
    Aug 11, 2001
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    #6
    Good for you. You might even see faster performance on the drive in the actual hard drive socket. Are you on a 2011 MacBook Pro which supports Sata III?
     
  7. JasonH42, Nov 28, 2011
    Last edited: Nov 28, 2011

    JasonH42 macrumors 6502

    Joined:
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    #7
     

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