Does the rsync/xdelta algorithm *need* to write a new file?

Arthur van Leeuwen
Thu, 23 May 2002 07:22:02 -0000

Hello,

lately I've been playing with the idea of doing in-place updates
of systems using either rsync or xdelta. However, both rsync
and xdelta seem to be dead set on writing a new file first, and
then atomically exchanging it with the old file.

Now, as I want to apply a binary delta to a full filesystem, bigger
than the available temporary space, this really makes rsync and
xdelta extremely tough to use (I could work around it, only updating
blocks of half the size of the temporary space at a time, but that
would defeat some of the savings gotten by calculating a delta over
the full filesystem: moves of data over block boundaries would incur
extra overhead delta's)

Has anybody thought about doing in-place patching of files using
delta's?

Another application where this would do wonders is people that rsync
complete ISO images: they would not need to reserve space for an
entire extra ISO on their systems.

Doei, Arthur. (Wondering if it is at all possible...)

--
+- Arthur van Leeuwen, Systems Consultant, arthurvl@xos.nl -+
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