Am 06. Nov, 2007 schwätzte Dan Lund so:

> There's an application called unison that'll take care of
> bidirectional synchronizations pretty easily.
> http://www.cis.upenn.edu/~bcpierce/unison/

Unison is great. I recently did a mini-presentation on it at a east side
meeting.

Unison doesn't handle hard links. That's probably fine for most people,
but doesn't work for some of my filesyncing needs.

Make sure to add "times = true" to the config! That makes it much easier
to figure out what's going on when you're reviewing the changes.

The only times I end up with conflicts is when a file was changed on both
sides between syncs. It gives you an opportunity to diff the files.

Unison can be run via command line and therefore via cron.

I also use unison to sync one data repository with several machines with
changes happening on each of the machines. Again it works unless a file
was changed on multiple machines prior to propagation.

You can choose to have unison take the default action and it'll move
things without conflicts ( including file deletions ) and leave the files
that are in conflict. Theoretically. I haven't actually gotten to the
point where I automate it that much.

Unison maintains a DB of the files in the repositories, so it can
determine if they've changed locally.

Here's info from the rsync manpage:

###
        To  synchronize my samba source trees I use the following Makefile
tar?
        gets:

            get:
                    rsync -avuzb --exclude ?*~? samba:samba/ .
            put:
                    rsync -Cavuzb . samba:samba/
            sync: get put

        this allows me to sync with a CVS directory at the  other  end  of
the
        connection. I then do CVS operations on the remote machine, which
saves
        a lot of time as the remote CVS protocol isn?t very efficient.
###

I don't know if that'll fit your needs.

There's also tra, but the whole 'this is experimental' thing and lack of
updates since 2002 keeps me from trying it :).

drsync - wrapper for file synchronisation via rsync
syrep - A generic file repository synchronization tool

Looks like syrep handles hardlinks, but not modification times or
permissions.

ciao,

der.hans

> On 11/6/07, Shawn Badger <badger.shawn@gmail.com> wrote:
>> I need to sync a folder on 2 servers, sounds easy, but the catch is that
>> they basically have to mirror each other. So if I deleted a file on one it
>> goes away on the other, but If I add a file it shows up on both. The catch
>> is that a file could be added or deleted form either system. Is there a way
>> to make rsync catch these changes and make sure they get mirrored? The other
>> option I am thinking about involves running a script that copies new files
>> to a "holding area" and point both servers to the holding area for the sync
>> source. the downside to that is I don't know how to handle deletes. I
>> haven't had much luck with Google on this yet, but I am still looking.

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