Recovering a RAID Drive that won't mount

Discussion in 'Mac Basics and Help' started by Dprime, Oct 8, 2009.

  1. Dprime macrumors newbie

    Jan 19, 2008
    Hey guys,

    Any advice on this would be throughly appreciated, I'm in a bit of a dilemma.

    I recently bought a Lacie 2big Raid drive with 2 x 1 TB drives for backup of my images (I'm a photographer).

    Everything was fine, mounted the drive, formatted, and used SilverKeeper to transfer all my previous work onto the drive which was formatted with RAID 1 (mirrored).

    The files all seemed to transfer across fine, size was the same, and I had a quick flick through the drive and images where all ok. So needing to use the drive that these images CAME off, I formatted that, and put that to use where it was needed.

    So in summary I had the Lacie RAID 1 as my 2 sources of backup at this point. I thought everything was fine at this point.

    Now maybe a few months on when I have to track back for files, I noticed quite a few folders had been corrupted, for example, opening a job folder, and every type of image file, jpeg's, tiffs, and PSD's would all say they are corrupt when I tried to open them in Photoshop. Some of these jobs where 20GB of RAW and edited images, all corrupt.

    So, reading through my manual for the Lacie, it said I could remove the 2nd drive, without altering the 1st drives data.

    With this I removed the second drive, trying to narrow out any problems with the RAID. Mounted the disc, same corrupt files.

    I then replaced the second drive back to the RAID, which the instructions said was fine, and it would just rebuilt the mirror, so I left if for a few hours while it rebuilt the second drive.

    Now my problem, the RAID has finished mirroring the drives, and now my MacPro or Powerbook won't let me mount the drive without formatting it which I obviously can't do, It brings up Disk Utility when the drive is switched on and wants me to format the drive to mount it.

    I guess my question is, is there a program that can force mount a drive onto OSX, so I can get access to this drive to recover it? I have all the recover programs needed once the disc is mounted, I just can't get it to that point.

    I just need to get the drive mounted first, then I can worry about the bloody corrupt files on it.

    Any help please?
  2. davegoody macrumors 6502


    Apr 9, 2003
    Reading, Berkshire, England
    OH Nooooooooo . . . . . .

    I Too am a wedding photographer, I have a 4tb RAID on FW800. Effectively there are a number of issues here . . .

    The Array should have been perhaps a backup for the originals, i.e. you should have COPIED the originals to another external drive rather than deleting them, hard drive prices are so low now, with 1TB usb2 Drives for £60 or thereabouts.

    You have compounded your issues somewhat by "breaking" the RAID. As much as you had some data corruption, before taking ANY radical steps to fix the problem you were best off backing up the only remaining copies of your data to another drive first.

    All easily said in hindsight though. A mirror is only as good as the weakest point in it's infrastructure, I had a similar issue a year or so ago, where the INTERFACE (FW400) was intermittently faulty. The same garbage corrupted files were written to both mirrored drives.

    You are now unlikely to recover data from the now broken mirror unfortunately, as the recovery process that the RAID underwent may well have overwritten data. I am uk based and may be able to help if you wish, having a lot of experience of these matter !

    Do you not have other partial backups of this data anywhere else ?

    You can email me on info at lifetyme dot co uk if you wish and I will try and help you recover something.

    Regards and good luck
  3. Dprime thread starter macrumors newbie

    Jan 19, 2008
    Thanks for the reply Dave,

    I decided to give up on trying to get the raid to mount, and put one drive somewhere safe so I can take that somewhere professional if I have to to have it recovered.

    I proceeded with a quick format on the 2nd drive, mounted it, and I scanned the drive with a program called StellarPhoenix, which seemed to pick everything up on the drive in its exact folder, so I hit recover (which cost me $99USD to buy the program) and it recovered all the files onto another drive for me, I thought I was blessed, but upon opening the recovery files, EVERY file is corrupt and wont open in photoshop.

    all the folders are in the correct position, as with the files, but the files are all corrupt. I found a program called FileJuicer, that can recover corrupted TIFF's and Jpeg's and when I apply that to one of the corrupted files, it recovers a file that is completely wrong. So for example if its a job that was a portrait of a person, it might recover a file that was from 2 months earlier of a landscape...

    Have you ever come across this? It seems as if the data is there, just not correctly?
  4. davegoody macrumors 6502


    Apr 9, 2003
    Reading, Berkshire, England
    Looks like a resource fork issue. . . . . .

    I have had similar issues, only once (and I can assure you that once was enough).

    OSX's disk format uses something called a resource fork to keep track of what is on the partition / drive and where it is stored. ( a little like the FAT system used by Windows systems, whereby the fork stores the location of the data and therefore knows where to find stuff) - if this gets corrupted, then the fork will point to the incorrect data.

    Hope I can help if you have further problems

  5. UltraNEO* macrumors 601


    Jun 16, 2007
    Hiya Dprime,

    Now depending on the state of your original RAID drive(s), it might be possible to recover the data but it won't be something you, yourself would do, simply because the catalogue has been erased via formatting. Of course you can try third party application such as Data Rescue II which might recover some of your data (regardless of your data fork being damaged or not). The alternative is to sending the drives to an data recovery service and have them read the erased data (it's possible because magnetic surfaces have memory). The pitfalls here, it won't be cheap... so it'll come down to - how much is the data worth?
  6. RHirabayashi macrumors newbie


    Jul 21, 2012
    Tampa, FL
    Recovering a RAID Drive that won't mount: FIXED!

    I was running a 2 x 2TB, RAID 1 on a FW800 enclosure, with over 600GB free. The array was listed as degraded in Disk Utility. I tried to rebuild the set, thinking it was just a logic error. When I saw the rebuild time was well over 3 days, I broke the mirror, thinking I would be able (as the message box indicated) use each drive separately.

    As it turns out, the enclosure died, and after I broke the mirror, neither volume would mount. No matter what I tried I couldn't get it to mount. The volume was greyed-out in the Disk Utility GUI, and Drive Genius wouldn't touch it.

    I searched for weeks, and finally found the answer here:

    In short, I ran 'diskutil list' from terminal and located a partition labeled "Apple_RAID_Offline".

    In my case it was '/dev/disk1' with an identifier of 'disk1s2' and an index of '2' and contents as 'GPT part - 52414944-5F4F-11AA-AA11-00306543ECAC'. The GUID-looking number in the contents refers to the type of partition, in my case "Apple_RAID_Offline" (source:

    Then I ran 'gpt show disk1' to list the partition data for '/dev/disk1'. This gave me the start and size. I copied the output to textedit then ran removed the partition manually with this:

    'gpt remove -1 2 disk1'

    This removed the partition data, not the volume contents.

    Then I re-added the partition with the type "Apple_HFS" with a GUID of "48465300-0000-11AA-AA11-00306543ECAC".

    The command looks like this:

    'gpt add -b *start* -s *size* -t 48465300-0000-11AA-AA11-00306543ECAC disk1'

    You'll want to replace *start* and *size* with the output from 'gpt show disk1'.

    The instant I did this, I could mount my drives!!

    Happy Partitioning!

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