Corupted Master File, or something like that

Discussion in 'Computer Information' started by Jeff Strickland, Jul 30, 2013.

  1. I have a secondary drive, Drive G, that my machine wants to CHKDSK at boot
    time, but the process fails with a message that reads CORUPTED MASTER FILE,
    or words to that affect.

    I've never seen a message like this, and I am not sure what it means. My
    instinct is that the drive is toast. I cannot see the drive after boot, so I
    cannot format. I have not tried to boot to Safe Mode, but I doubt this will
    help me gain access to the drive.

    It's a SATA drive, and I can see it with Safely Remove Hardware, but I have
    not done this. I can remove the drive and then put it back in, I suppose.

    What does the message mean?
    Jeff Strickland, Jul 30, 2013
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  2. When I use Windows Explorer, the dialog box reads, G IS NOT ACCESSABLE. THE

    I used Safetly Remove Hardware to remove and reboot, and the errors remain
    the same.

    Dead drive?
    Jeff Strickland, Jul 30, 2013
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  3. Jeff Strickland

    Paul Guest

    It sounds like the drive is still there.

    You might want to enter Disk Management, and see if the disk appears there.

    You couldn't very well make that much progress in CHKDSK, without
    the partition being slightly readable. The partition header must
    still be there.

    It sounds like a reference to $MFT, the master file table of an NTFS partition.
    There is a backup MFT, but it is a stub, and basically just points to the
    beginning of some structure, rather than being a complete copy. And as such,
    I don't really understand its purpose, or how it buys you anything.


    Describes all files on the volume, including file names, timestamps,
    stream names, and lists of cluster numbers where data streams reside,
    indexes, security identifiers, and file attributes like "read only",
    "compressed", "encrypted", etc.


    Duplicate of the first vital entries of $MFT,
    usually 4 entries (4 Kilobytes).

    I don't really know what to tell you with respect to fixing it.
    CHKDSK is the only tool I know of. A file scavenger could scan
    the disk and attempt to find files, but as far as I know, that
    would only be 100% successful, if the partition was zero percent
    fragmented (each file is completely contiguous).

    TestDisk is a tool to solve another problem. It rebuilds the partition
    table (pointer to partitions on disk, stored in sector 0). Your problem
    is not locating the partition, because you made it far enough to find
    a $MFT problem (your partition header must be intact and being pointed
    to properly). But TestDisk happens to have a "file viewer" option.
    In your case, the file viewer should fail, because the file viewer
    would need the services of the $MFT.

    Part way down that page, you'll see this picture. It
    shows the tool listing files on a partition. That's a form
    of proof a partition is relatively healthy. TestDisk is not
    a partition repair tool. It's more interested in the health
    of sector 0, and various repairs to sector 0 (partition table,
    boot code).


    In terms of throwing out the drive...

    You could review the SMART stats for the drive, with HDTune Health tab.
    Look for Current Pending data field, or Reallocated Sector Count data field,
    and see if the drive is in trouble.

    This is what I look for. The two values marked by red boxes should be zero.

    The yellow marks the tool has left here, happen to be irrelevant. So while
    a yellow mark can be "for real", typically they're not. All my drives show
    two or three yellow marks, but they all turn out to be bogus. If you had
    enough reallocated sectors though, that one would eventually turn yellow.

    Paul, Jul 30, 2013
  4. Jeff Strickland

    - Bobb - Guest

    There's part of drive where the drive "keeps track of where everything is":
    the master file table .

    If one file is contiguous then the entry would be start sector, end sector.
    If another file is broken into 5 pieces then it would have 5 "pointers".
    That area on the drive where this all gets written is the master file
    table - like scribbling on a piece of paper while organizing things. If that
    fills up then you cannot complete your task.

    On an XP box, on a good drive -in windows right-click on drive =
    properties - run defrag - then analyze - click VIEW REPORT and you'll see
    defrag info AS WELL AS the MFT info. If drive gets TOO fragmented, and gets
    full, then the MFT fills the allocated area. and no room on drive to
    "scribble notes any longer."

    Try to boot a knoppix CD and see if IT can read the 'bad drive'. Its access
    procedure varies a bit. I have saved a few drives ( years ago) by doing
    that.( not sure if MFT problems though). If so, copy all you can. OR you
    MIGHT delete a lot of unneeded stuff to make room on drive and try to
    reformat. If surface damage then it's gonna be unreadable.

    scroll halfway down there to
    Understanding what CHKDSK does

    Good luck.
    - Bobb -, Aug 22, 2013
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