RAID-1 with external drives

Discussion in 'macOS' started by saltyzoo, Mar 25, 2008.

  1. saltyzoo macrumors 65816


    Oct 4, 2007
    Has anybody had any success doing software RAID 1 with external USB drives on 10.5.2?

    I tried it last night and boy howdy disk utility was bugging out all over the place on me. It got to the point where every operation I did, I closed disk utility and re-opened it because half the time it showed something different after a restart.

    Here's exactly what I was trying to do. I have two USB external drives, both partitioned with two 250 gig partitions. Actually, the second drive has 3 250 gig partitions, but the 3rd I'm not planning on using for RAID. After 6 or 8 attempts I was able to get the first partition of each drive in a RAID 1 set. However, I was never able to get the second partitions to work in a second RAID set. Disk utility did all sorts of crazy things, but none of them were ever creating the RAID set properly.

    I realize this is sort of a strange thing to do (have two partitions on a drive in two RAID sets), and it wouldn't bother me much if disk utility just wouldn't allow me to do it. But the fact that it "tries" but bugs out and half does it really scares me that this isn't going to be reliable RAID 1. And that is the point isn't it?
  2. CanadaRAM macrumors G5


    Oct 11, 2004
    On the Left Coast - Victoria BC Canada
    Tremendously bad idea.

    USB 2.0 is slow for drive transfers. It eats up CPU cycles to manage the drives. Add on top of that the software RAID overhead. Now add the inherent risk of RAID 0 times the unreliability of USB, external drives and cabling, and you have a recipe for disaster.
  3. saltyzoo thread starter macrumors 65816


    Oct 4, 2007
    Well, I understand what you are saying, but it there's no reason why it has to be a bad idea. It is more than possible to do it if you code around the issues properly. But based on my experience so far, I'd say they haven't done so yet.

    edit: Ok, sorry, I'm an idiot, I meant RAID-1 not RAID-0. duh. Yeah, you'd be an idiot to do RAID-0 with external drives. Not what I was trying to do.

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