[Dovecot] rsync'ing maildir (Was: Cyrus MailDir to Dovecot mbox)

[Steinar Bang]

>>>>> Steinar Bang <sb at dod.no>:

> I can see one issue with it, when using rsync to back up the mailboxes
> to a different machine:
> since the file names of the articles change when they are read, and when
> the state changes, rsync may ending up transferring the same article
> more than once (unless it has some clever checksumming to recognize
> files that may be the same when the name has changed), but in practice I
> don't think that will be much of a problem.

I googled for rsync and maildir, and found this:
	http://www.nabble.com/Rsync-snapshots,-Maildir,-and-Sarbanes-Oxley-td11914169s24859.html

It mentions using the --fuzzy flag.  From the rsync man page:
       -y, --fuzzy
              This option tells rsync that it should look for a basis file for
              any  destination  file  that  is missing.  The current algorithm
              looks in the same directory as the destination file for either a
              file  that  has  an identical size and modified-time, or a simi‐
              larly-named file.  If found, rsync uses the fuzzy basis file  to
              try to speed up the transfer.

              Note  that  the  use of the --delete option might get rid of any
              potential fuzzy-match files, so  either  use  --delete-after  or
              specify some filename exclusions if you need to prevent this.

(and a note to myself on the last bit: I'm currently using --archive
--delete, so that's something to look out for.  I guess that my new
arguments will be --archive --fuzzy --delete-after)