Data Recovery From RAID 0 Array?

Discussion in 'Mac Basics and Help' started by beerstine, Feb 16, 2007.

  1. beerstine macrumors newbie

    Joined:
    Jul 18, 2002
    #1
    It looks like I've had a drive failure with at least one of my 2 month old Maxtor Maxline Pro hard drives striped in RAID 0. It dismounts shortly after startup and DiskWarrior won't even fix it.

    Has anybody had any success with data recovery software involving RAID 0 striped arrays? Most of the options that I've seen including Data Rescue 2 don't claim to work on RAID volumes. There's a new piece of software called Boomerang that claims to, but It's $180 and I don't want to put down that kind of coin unless I have some feedback as to whether it really works (It runs in demo mode, but I can't tell if it will actually recover anything usable).

    About 80% of the data on the drives is backed up but some of my most recent work (mostly audio and video files that would take a long time to recreate), is still on the drive and I'd like to cherry pick them off before replacing the drives.
     
  2. ElectricSheep macrumors 6502

    ElectricSheep

    Joined:
    Feb 18, 2004
    Location:
    Wilmington, DE
    #2
    I haven't heard anything about Boomerang...

    Just from a developer's standpoint, recovering data from a RAID 0 array in which one drive has failed is a technical challenge. I'd need to know what the underlying stucture of the RAID array was (block level striping, how large each element in the array is, in what order the blocks are reassembled into a conitguous data stream).

    Its conceivable to use the command line utility dd to recover the data...but not without a custom C program to post-process the extracted information in preparation for scanning with data recover tools. I'd take the approach of creating a block level image of the failed drive, and a block level image of the working drive. Then, use a piece of custom software to 'de-interlace' the blocks from each image, producing a single image of contiguous blocks. But, that's not so straitforward without knowing about how the filesystem handles the RAID 0 array.

    It really looks like you are up a creek, and have learned a painful lesson about running a RAID 0 array. RAID 0 isn't even a true level of RAID. There is no fault tolerance. There is no redundancy. In fact, the likelyhood of failure with RAID 0 is higher than with a single drive.

    RAID 0 arrays should only be used for scratch work, and should not contain the only copy of your data.

    You're other mistake was to use Maxtor drives. I've had nothing but trouble with Maxtors and have seen nothing but trouble in those around me. I've got a lengthy list of clients/friends/acquaintences who have lost data from a failed Maxtor. I avoid them and stick with either Western Digital or Seagate.

    If you want the performance of a Striped array without sacrificing fault tolerance, consider a hardware based RAID 5 solution.
     
  3. beerstine thread starter macrumors newbie

    Joined:
    Jul 18, 2002
    #3
    I was running RAID 0 as a scratch disk for video editing where speed was the primary concern. I had few project files on there but there is a lot of video that would take many many hours to reimport or recompress. I was hoping to get around at least some of that.

    As for drive brand, that seems to be one of the most subjective things out there. I've had Maxtor drives run every day for 4 years without a glitch. The Western Digitals I've had all crapped out in under 6 months, one in less than a month. Buying drives is a crapshoot.
     
  4. acsdata macrumors newbie

    Joined:
    Feb 18, 2007
    #4
    In order to properly recover the data from the stripe, you're going to have to have access to both drives. If one drive is dropping out, then it may have an underlying mechanical or electrical issue that would need to be corrected first.

    Mac file systems are extremely delicate and very prone to data corruption in this type of failure when the data is striped among one or more disks. If the stripe is skewed then the file system may be rebuilt but the data itself may be corrupted. There are some generalized tools out there that might help you, but the process is fairly complex, and could render the data unrecoverable if not performed correctly. It also depends on the nature of the failure, if the drive has a mechanical problem there's really nothing more you can do. It really comes down to how valueable the data is. If it's worth $1,500 to $2,000 that's probably a safe bet on what a recovery like that would cost, and you're better off not doing anything else that might make the data unrecoverable.

    If it's not worth that much, then see if you can get the drive that keeps dropping out to stay up long enough so you can image it to a good working drive. You'll need to find some software out there that would make a good sector-by-sector clone of the drive, and can bypass sector read errors. Make sure you make an image of both drives first, and then set the originals off to the side and don't touch them. Once that process is complete, then you will have eliminated one part of the problem, which is the faulty drive. You'll then need to find a way to destripe the cloned drives, and then you'll need to find a pretty robust recovery program made for mac so that you can do the actual recovery. I can't really recommend any, because I've never used them and all of the software we use, we have developed ourselves. I'm just trying to let you know how you need to proceed, and what steps will need to be taken.
     
  5. beerstine thread starter macrumors newbie

    Joined:
    Jul 18, 2002
    #5
    Thanks Greg for the explanation of the process. Very useful to know for the future.

    In my case, most of the data is either backed up or can be reimported from tape or DVD (though it will cost me many hours to bring it back online). I was hoping to recover some recent work, but it's not worth $1500 for just that.

    I've tried demos of the available Mac recovery solutions and most will not work on a RAID of any kind.
     
  6. acsdata macrumors newbie

    Joined:
    Feb 18, 2007
    #6

    Yeah unfortunately there's really not a lot you can do with most of the Mac software that's out there, at least not until you get the failed drive working and then destripe the data. Once those two obstacles are conquered then it's pretty much a standard recovery process.
     
  7. superbovine macrumors 68030

    superbovine

    Joined:
    Nov 7, 2003
    #7
    online data recovery. you hook up they will see if they can fix. get a live quote from engineer.

    http://ontrack.com/rdr/
     
  8. vzzz macrumors newbie

    Joined:
    Feb 23, 2007
    #8
    DataRecoveryWizard

    I recommend that you use EASEUS DataRecoveryWizard to recover your data.
    The software provides very useful functions for data recovery:
    DeleteRecovery, FormatRecovery, AdvancedRecovery, RawRecovery.

    This program is an efficient disk recovery software providing
    you a complete answer to data loss.

    You can download the demo version of EASEUS DataRecoveryWizard.
    http://www.easeus.com/download.htm

    Run the program and you can select the any recovery mode
    "DeletedRecovery", "FormatRecovery" and "AdvancedRecovery".

    See more:
    http://www.easeus.com
     

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