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"Backup" very big file

  • Hi all!

    I have this problem: I need to make a password-protected, non-compressed zip file of a folder containing

    about 50-70 files of various size, from 1kb to (wow!) 6Gb!!!

    I have downloaded 7-zip 4.11 beta, and I have tried this metod:

    d:\myfolder>7za a -mx0 -pmypassword -r -tzip -wd:\ -xr!notthissubfolder -y d:\myzipfile.zip

    After about 10 min of "milling", 7-zip created a zip file of approximately 7Gb (pew!)... the problem is

    that if I try to open this file with any other zip program (like winzip, winrar, winace etc), all they say

    "Unexpected end of file" or "Wrong ID Header" or other errors...

    Bypassing this problem, winrar shows me the list of the files contained in the zip... that is interrupted

    in correspondence of the file of 6Gb!!! In any case I cannot extract files from the archive: winrar say me

    "Damaged archive" :(

    So, I have tried to make the zip compressed "just a bit" (-mx1), but the result is the same (and 35 min of


    I know, many of you will say me "use the 7z format!", but for "business reasons" (...) I'm forced to use

    the zip format :(

    Nobody has idea which can be the problem? My OS is NT Server 4.0 SP4.

    Thanx to all in advance... and sorry for my terrible english :)


    • Igor Pavlov
      Igor Pavlov

      Maybe my implementation of Zip64 is not correct.
      Check that archive with latest PkZip and latest WinZip.
      If it fails, try to reduce file set (maybe to one 5 GB file) and check again.

    • Igor Pavlov
      Igor Pavlov

      I've found one bug in new Zip64 code:
      7-Zip created incorrect ZIP archives if file size was from 3.75 GB to 4 GB.
      Have you such files?

      Please write fixed version of zip.dll to "Formats" folder and try again:

      • Hi Igor!

        Now it works fine! Thank you very much!

        I have tested the archive (created with the new dll) with the latest version of WinZIP 9, and the zip was decompressed correctly.
        Curiously, WinRAR 3.30 continues to say me that the archive is damaged... wrong Zip64 implementation also for they? :)

        If it can be useful for you, this is my actual situation:

        1) one big file of bytes (destined to increase...)
        2) approx 190 files, with dimensions from some bytes (min) to 5.120.000 bytes (max)

        Just a question: have you planned to eliminate the bug also from the standalone version?

        Thank you very much!!!


        • Igor Pavlov
          Igor Pavlov

          Check version 4.12 beta.
          The most problem case was for files with size from 3.75 GB to 4 GB.