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.
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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
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
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
Any comment is welcome.