some thoughts about gmirror

Matthew Seaman m.seaman at
Sat Apr 7 07:34:37 UTC 2007

R. B. Riddick wrote:

> Sounds like rsync can already do that (I am not sure right now, if rsync can
> find updated areas within a large file, or if it just copies the while updated
> file even if it is a large one)...

rsync will find an updated area within a big file.  The algorithm is to
divide any such file into 100kB[*] chunks, calculate checksums of each of
those chunks and only transfer the chunks where the checksum differs
between source and destination.  More detail here:



[*] For some value of 100kB.

Dr Matthew J Seaman MA, D.Phil.                       7 Priory Courtyard
                                                      Flat 3
PGP:         Ramsgate
                                                      Kent, CT11 9PW

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