Wayne Davison (way...@samba.org) wrote on 4 July 2011 17:10: >On Sat, Jul 2, 2011 at 5:46 PM, Carlos Carvalho <car...@fisica.ufpr.br> wrote: > > When --checksum is used they're calculated in both ends to see if the file > should be transfered. This is of course not necessary if the file doesn't > exist in the destination. However, the checksum is still calculated by the > sender, which is often a very large overhead. > > Would it be possible to avoid it? > > >To do so would involve adding an extra round-trip request to a transfer, so it >is feasible, but is not currently supported. [...] >That all sounds interesting, but would require a new >--favor-missing-files (or some such) option to tell rsync to use the >alternate checksum method. It would be interesting to try something >like that and see how much time it saves in checksum generating vs >time it consumes in round-trip lag.
Understood. I asked just in case it was an easy optimization but it looks like some significant complication for a rather rare use. >As for what is currently possible, see the patches/db.diff, patches/ >checksum-reading.diff, patches/checksum-updating.diff, and >(possibly) patches/ checksum-xattrs.diff patches for example ways to >make the checksum sending more efficient. I can't use this because we're the destination and the origins are spread all over the world. Instead I've separated the files we need to checksum and do them in a different rsync run. Thanks for the detailed explanation. -- Please use reply-all for most replies to avoid omitting the mailing list. To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html