I have a damaged "B-tree" what the hell does that mean?

Discussion in 'MacBook Pro' started by WillMak, Mar 19, 2007.

  1. WillMak macrumors 6502a

    Jul 29, 2005
    My external harddrive got damaged while I was doing a system update. When I run disc utility for repair I can't mount it anymore because of a "b-tree." What does this mean and can I save my external harddrive?
  2. deadpixels macrumors 6502a


    Oct 30, 2006
    if you launch 'disk utility', does it see your harddrive? if yes then try to repair it. i've had damaged b-tree quite often, although i don't know what it exactly mean i was always able to get it repaired :D
  3. deadpixels macrumors 6502a


    Oct 30, 2006
    an interesting thread here.
    it seems that disk utility might not fix it, although you should try it, run it from the install disks. next step is DiskWarrior.
  4. RoxStrongo macrumors regular


    Oct 8, 2005
    Bournemouth, UK
    a similar thing happened to me, although i was totally unable to repair it. in the end i used a program called data rescue x. it got almost all of my stuff back in perfect working order. i then had to wipe the drive.
    good luck.
  5. Multimedia macrumors 603


    Jul 27, 2001
    Santa Cruz CA, Silicon Beach
    Disc Warrior Might Work

    DiskWarrior 4 is pretty good at fixing B-Tree types of damage.
  6. MaaseyRacer macrumors regular

    Oct 30, 2005
    San Francisco, Ca.
    You will probably have to use Disk Warrior or the system CD to recover your data to another drive, and then repartition that drive to get it running again. Personally I would recover to another drive and throw the problematic drive away. Hard drives have a short life span, no need to keep around a device that is showing signs of failure.
  7. IJ Reilly macrumors P6

    IJ Reilly

    Jul 16, 2002
    I agree with the use of Disk Warrior to repair b-tree errors, but certainly not with throwing the drive away. :eek: These kinds of errors can be created in all sorts of ways not related to hardware failure. With the right recovery tools, they can be easily repaired, and the drive won't even need to be reformatted in order to sail along happily for many more years.
  8. ChrisA macrumors G4

    Jan 5, 2006
    Redondo Beach, California
    "b-tree" is short for "balanced tree". I'm surprized Apple would present such an unimportant technical term to a user.

    The way a "tree" works is simple. Lets say you want to find someone by their last name so you build an index that reads for "A-L" go to room 5 for "M-Z" go to room 10. Then inside room 5 you see a sign that reads "for A-G go to room 2, for H-L room 3" Now where the "B" or "Balance" comes in they add one more little detail -- they adjust the letter ranges so that at each decision point the two groups of people are equal. This means that they have to switch the signs a lot as people come and go in and out of the system but if you do this you are always certain to have the minimum number of levels before you find the person.

    How does it know the b-tree is broken. maybe a "room number" points to a room that does not exist. Maybe the letter on the left is higher than the letter on the right. Maybe some sequence of signs lead in a circle. May in the A-K room you see a Q-S sign. When the file system is mounted it looks for errors like these and a few more. Either way it can be fixed by simply scanning all the people, reassigning them to rooms and writting all new signs.

    Of course on the disk "people" are files and "rooms" are blocks of disk sectors.
  9. FF_productions macrumors 68030


    Apr 16, 2005
    Mt. Prospect, Illinois
    Ouch I had a damaged B-Tree because I pressed a button in TechTool Pro and lost all the information on my drive (I didn't feel like paying to have it all recovered).

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