B-Tree errors & Data Recovery on External Hard Drives

Discussion in 'Mac Accessories' started by musemelodic, Dec 22, 2010.

  1. musemelodic macrumors newbie

    Dec 22, 2010

    I am writing about my friends computer. He has a Macbook Pro and the other day had an Iomega 500GB plugged into the 800 firewire port. He for some reason accidentally pressed down hard on the drive, heard a grinding sound and it was no longer recognizable by the MAC HD. So, he then consequently plugged in his other backup drive to begin to make a clone, which is a LaCie External, and that drive then got corrupted when he plugged it in. So now, no backup what so ever. :mad:

    Tonight, he went to an appt. with an Apple Genius Bar worker and they told him it was a coincidence and that once his Iomega was corrupted and he tried to boot the LaCie off of that, it corrupted the other drives too. He told my friend he has B-tree errors and needs data recovery on the external hard drives and that could be done.

    My question is can he do this himself with an $100 program or does it pay to bring it into someone? He doesn't have a lot of $$$ to spend unfortunately so that's the issue. If anyone has dealt with this problem and has had a satisfactory outcome, please do not hesitate to advise!
  2. Fishrrman macrumors G5


    Feb 20, 2009
    "My question is can he do this himself with an $100 program or does it pay to bring it into someone? He doesn't have a lot of $$$ to spend unfortunately so that's the issue."

    Unless I'm mistaken, "B-tree errors" refer to problems in the drive's directory itself, not so much with the actual data that is contained on the drive.

    There are two approaches that I can see:
    1. Try to repair the directory itself using DiskWarrior, or,
    2. Bypass the directory by using file recovery software like DataRescue3 or Stellar Phoenix Data Recovery.

    DiskWarrior _may_ be able to repair the damaged directories, but there's no guarantee. It does have the advantage that (if it works) you don't have to buy another drive to which to recover the data.

    File recovery apps like DR3 and SPDR "go right to the heart" of the matter. They are designed to work around or literally ignore the directories, and go right to the drive's sectors and "scavenge" whatever they can find there. You WILL need a SECOND, fresh hard drive on which these apps can write the information they find. So your friend is going to have buy another hard drive as well. I would suggest getting a "bare" drive and using it in conjunction with a "USB/SATA docking station" (plenty of these to be found at amazon.com and everywhere else).

    Be aware that with a completely corrupted drive directory, it may not be possible to mount the drive to where even apps like DR3 and SPDR can "see" the drive (and then "attack" it). It is STILL POSSIBLE to get at the data, however, by:
    1. reinitializing the drive (yes, re-initializing it)
    2. IMPORTANT: DO NOT "zero out" the data, just use the "erase" option
    3. This wipes out the directory and replaces it with a new (empty) one, but DOES NOT actually zero out the data that's already on the drive sectors.
    4. NOW it becomes possible to mount the drive on the desktop, and once mounted, DR3 and SPDR can go to work and "do their things".
    The above technique should only be used as a LAST RESORT. It worked for me when nothing else seemed to revive a damaged partition I had.
  3. musemelodic thread starter macrumors newbie

    Dec 22, 2010
    Thank you for your reply.

    When he brought it into Apple, they said they could see the drives which came up as soon as they plugged them in, but couldn't read them because of "fatal b-tree errors/cannot read this drive" So, the fact that the drives came up fast was a good sign, they just cannot be read. I don't know if Disk Warrior is good at being consistent with repairing such things or not.

    He is talking to a Unitek guy today and hoping to get more advice. I will follow up on what does or does not work so that anyone else that has this problem can come to a better conclusion about how to handle this as well. If there are anymore suggestions, please don't hesitate to chime in! :)

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