unpack a file that has no compresion
Page 1 of 2 12 LastLast
Results 1 to 10 of 15

Thread: unpack a file that has no compresion

  1. #1

    unpack a file that has no compresion

    I was hopeing someone here could sugest a fix to this problem.

    I had backed my moms files up prior to a format, in which case I decided it would be faster to zip them with no compression. I figure this just stores the files into one large file. Since all together the size is 2.5G I then split this large file into three parts and burned them to cd with an unsplit program

    after the format i was able to unsplit them back into the one large 2.4G file, but now i need to get all the small files inside, out and back to my documents. However the zip program (ZipGenius) is unable to read the file and reports the contents as blank. I assume this is because there was no compression used and ZipGenius thinks it is looking for a compresed file. I read the help files and discovered it used a command line 7zip utility to pack the files with the no compresion, but found nothing on how to retrieve the files.

    The documentation for 7zip does not even mention retrieveing files after they have been stored into a large file.

    I have emailed the suport team with no luck, and tryed a few other zip programs hopeing one would recognize the format as uncompressed and alow me to retrieve the files.

    I am very much at my wits end and mom is gona scream if i tell her i cant get the files back out.

    I even contimplated reading the format of the file with a hex editor, finding any delimiter character that seperates file data, and maybe writeing a big loop that seperates the files but i realy dont know how many hours it would take to do this since it is a 2.4GB file

    Please help anyone.
    test

  2. #2

  3. #3

  4. #4
    Just finished trying Comparex, I even downloaded the extra packages, but it is unable to open the file, says unsuported type.

    winrar nor winzip were able to open the file, even ZipGenius which created it was unable to open.

    Ive been thinking maybe it is damaged but dosent make sence since the size of the my documents before the process was 2.4G and afterwards the single file is 2.4G which is why i assume that it is not corupt but rather in some strange format.

    I know that ZipGenius www.zipgenius.it used a command line version of 7zip to create this uncompressed file, and I did see the dos screen of 7zip when i created the archive and there were no errors, I seen each file go in.

    I can find the command line options to do it again but not to undo whats already done
    test

  5. #5
    maybe if i use zipgenius again and this time only pack 3 files with the no compression then maybe i can post the sceen shot and the file as an atachment

    ill do that in mourning when my brain is more active
    test

  6. #6
    Senior Member
    Join Date
    Jul 2004
    Posts
    469
    My guess would be the file is corrupt. Just because the file size matches doesn't mean the data is still good. Also, in your original post you said it started at 2.5g and now 2.4g. If that wasn't a typo then that is probably your problem. If you zip a file with a program, you can most likely unzip it with the same program. The compression format should have nothing to do with it. You could have had corruption in the zipping process, in the splitting process, in the burning process, or in the joining process. That is a lot of processing for such a large file. You might also want to check into what the maximum size file is for that program. Some file types have maximums. You can create a file larger and it will seem like it works, but when you try to use that file it will show as corrupt.

  7. #7
    Senior Member Zonewalker's Avatar
    Join Date
    Jul 2002
    Posts
    949
    just one thing which may be stating the obvious but which I think should be said...

    'Always, always check the integrity of a backup before you delete the original files!'

    Something to keep in mind for all of us.

    Z
    Quis Custodiet Ipsos Custodes

  8. #8
    Junior Member
    Join Date
    Aug 2002
    Posts
    9
    Check your filesystem. If the file is 2.4 G, If you are using a fat32 filesystem, strange things will happen.

    Fat32's max file size is 2 GB. I've been able to save larger files on a fat32 system, but then they were garbage. I'm assuming this is because it looses the pointers to the rest of the file.

    The backup may be intact. Just make sure you are operating on an ntfs based system, then try it again.

    WinXP doesn't allways default to an NTFS, they sometimes format the hd as fat32. to convert to ntfs:

    convert drive letter: /fs:ntfs

    If you have imagemagic setup, you will have to give an absolute path to convert.

    Good Luck.
    JT
    Jay C. Theriot

  9. #9
    Master-Jedi-Pimps0r & Moderator thehorse13's Avatar
    Join Date
    Dec 2002
    Location
    Washington D.C. area
    Posts
    2,884
    You might also want to check into what the maximum size file is for that program. Some file types have maximums. You can create a file larger and it will seem like it works, but when you try to use that file it will show as corrupt.
    This is most likely your problem. Compression utilities and those that create uncompressed archives are notorious for creating archives outside of their limit threasholds. Call or e-mail their support team and ask about the archive limits. This may be broken out into several catagories, including directory structure, total archive size, number of files within an archive, etc., etc..

    --TH13
    Our scars have the power to remind us that our past was real. -- Hannibal Lecter.
    Talent is God given. Be humble. Fame is man-given. Be grateful. Conceit is self-given. Be careful. -- John Wooden

  10. #10
    Senior Member
    Join Date
    Oct 2001
    Posts
    748
    Originally posted here by jtheriot
    Check your filesystem. If the file is 2.4 G, If you are using a fat32 filesystem, strange things will happen.

    Fat32's max file size is 2 GB. I've been able to save larger files on a fat32 system, but then they were garbage. I'm assuming this is because it looses the pointers to the rest of the file.

    The backup may be intact. Just make sure you are operating on an ntfs based system, then try it again.
    JT

    Not correct at all. The max file size on fat32 is 4GB. And the file will not corrupt, no pointers are lost, the file just will not grow anymore. Consider it to be write locked. A 2.4gb file on fat32 will cause no problems at all.

    More than likely the utility you used to split the original archive did not put the files back together properly. If that utility doesn't do a CRC check before and after the "split." I wouldn't trust the data to be uncorrupted. In the future I would stick to winzip or winrar as they are really the best utilities for windows. Winrar is probably the best for splitting up a large file into many smaller files.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •