• WARNING: DomBackup creates unreadable zip archives from files > 2GB (i.e. data will be lost) on Windows platforms!

    By Andreas Meyer-Durand 10 months ago

    The ZIP-compression option in DomBackup is still
    experimental as it doesn't include large-file support (i.e. > 2GB)!
    This limitation applies only to Windows platforms.mso-fareast-font-family:"Times New Roman";mso-ansi-language:EN-GB;mso-fareast-language:
    FR”>

    With DomBackup, Ulrich Krause has made a great work
    and delivered a very nice piece of software. However I think it is crucial to
    inform admins and developers of this potentially

    dangerous flaw.

    As a matter of fact, DomBackup CAN NOT compress files
    bigger than 2GB correctly.

    The reason for this behaviour is that the underlying
    compression code (used to implement the zip compression in DomBackup) is based
    on the “Info-ZIP” code (which was modified by Lucian Wischik,
    code available at http://www.info-zip.org and http://www.codeproject.com).
    Lucian's code does not allow for a correct compression of files > 2GB. It
    doesn't allow for the correct compression of files > 4GB either because the
    Zip64 extension is not implemented (http://kb.winzip.com/kb/entry/99/).

    Unfortunately, Domino administrators may not be aware of this important restriction due to the fact that DomBackup creates archives from files > 2GB without an error message. I.e.: you'll get a zip archive which seems to be fine but which is in reality unreadable.

    Workaround: DO NOT use the zip compression option on Windows platforms.

    At the end of the backup cycle, backup files should be
    renamed (in order to be able to distinguish those backup files from the original nsf/ntf
    files).

    Any comment is welcome.

    • By Ulrich Krause 10 months ago

      The issue is fixed. I have replaced the existing zip routines with http://www.zlib.net/

      Files > 2GB can now be moved to an archive and extracted from an archive without any problems.

      I will upload the new release during the next days.