"un"format

This is a discussion on "un"format within the A Brief History of Cprogramming.com forums, part of the Community Boards category; A friend of mine accidently formated a harddrive that contained all of his backups. Is there a way to retrieve ...

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    Banned maes's Avatar
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    "un"format

    A friend of mine accidently formated a harddrive that contained all of his backups. Is there a way to retrieve the data from the formated disk?
    I think this was asked before, but I can't find the thread.

    What program should he use?

    there's nothing on the disk. he hasn't used it since the format. (so he didn't overwrite the formated data if this can be of any help)

    thx


    --Maes

  2. #2
    mov.w #$1337,D0 Jeremy G's Avatar
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    Only recoverable if your the super secret cia !!!
    c++->visualc++->directx->opengl->c++;
    (it should be realized my posts are all in a light hearted manner. And should not be taken offense to.)

  3. #3
    Super Moderator VirtualAce's Avatar
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    Yes there is, but its not easy. You will have to either download a program that will do this or code your own. To make the format function faster, MS did not ensure that all data would be erased, just that it would not 'appear' to be there. In worst cases only the first cluster is missing and in the best case only the first letter of the file has been removed which will cause dir to think its not there.

    The process would be to manually scan the FAT and trace the cluster chain for each file until EOF. You could write the data to another disk while doing this, but thats harder than just dumping the contents to a buffer and then creating a file from the buffer.

    Trace the chain and compile the broken chain, if it is, into a file. Call DOS to actually create an empty file and then dump the contents of the clusters (the buffer data) into the file. You know what order to dump them in because of the cluster chain. This should create your new file with your old data.

    This is only pertaining to FAT file systems. There is not a lot of free/public information about NTFS out there so I'd be lost as to how to do this on that file system.

    Code:
    ...Find file in directory - first letter will be altered
    while not(EOF)
    {
       ...Retrieve current cluster number from FAT
       ...Retrieve data at current cluster
       ...Add contents of cluster into buffer
       ...Dump <cluster size> bytes to the buffer
       ...Increment buffer position by <cluster size> bytes
       ...Advance to next cluster
    }
    ...Call DOS or Windows to create a file
    ...Dump contents of buffer into file
    
    File should be restored at this point.
    To write this on your own you will need a lot of low-level interface functions that use int 13h and LBA addressing.

  4. #4
    Banned maes's Avatar
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    >>low-level interface functions that use int 13h and LBA addressing
    Doing it myself is probably not a good I dea, it would take me years to learn that stuff. the lowest stuff I know is fopen .

    guess we'll go looking for a program then.

    >>Only recoverable if your the super secret cia !!!
    Perhaps if we say that we have discoverd the perfect way for nuclear fusion and mail them the HD, they'll do it for us

  5. #5
    Quietly Lurking
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    My best suggestion, Check here , you can try a free version of their software which will atleast show you what could be recovered, and then decide if you want to shell out a couple hundred dollars for data recovery software.
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    RoD
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    Redundantly Redundant RoD's Avatar
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    try a board search this has been extensively explained in tech a few times.

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    PC Fixer-Upper Waldo2k2's Avatar
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    maes,
    email me to remind me, it's going to be a busy week, but i have one of the older free versions of some data recovery software. If it's fat, it'll find it. I'll send it via email so just write me and i'll getto it soon (note, run it from a different hdd )
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    Registered User FloatingPoint's Avatar
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    If you already have PartitionMagic there's this unformat command from one of the drop down menu. Could be useful too...
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  9. #9
    Its not rocket science vasanth's Avatar
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    i wouldnt suggest Ontrack.. it cant recover everytin.. i would sugges you connect your hard disk to another pc and install the software on the local system and try to recover the data on your disk.. The software name i guess is Partition recovery pro or sometin.. it did a wonderfull job.. recovered all my data from a formated hard disk.... I even herd norton has some software for this...

  10. #10
    Banned maes's Avatar
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    thx guys we'll try those programs

    --Maes

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