Auto-backup from remote server to local server software?

I'm looking for software that will auto-backup files from a remote server to a local server ONLY if they have been modified or added. Otherwise they will not do anything. Is there any software available like that?

From serverfault kylex

• I use this:

  http://www.retrospect.com/

  It sits on an OS X server connected to an Exabyte tape drive, and I have it backing up data from OS X and Windows servers alike... It can be configured to perform backups as you have described...Not cheap or open-source, but I've found it to be reliable..

  From CaseyIT

• You're referring to "incremental backups". Assuming your looking for something open source checkout bacula or backuppc. Backuppc can have a bit of a learning curve but it works great. R1soft is awesome (bare metal restores) but it is a commercial product.

  From CarpeNoctem

• If you want a tool that does this specific job (and not a full-fledged backup suite), look at rsync. You can invoke it with a scp-like syntax, and it does checksum-based incremental transfers .

  From b0fh

• In addition to the rsync answer I can totally recommend rdiff-backup. It is based on rsync, works across different operating systems and file systems and is absolutely reliable. I use it myself to back up different computers to different others, across local networks, the internet and dial up lines. But the nicest feature (for me, YMMV) is the easy restore of data at any given point back in time. Almost as cool as Mac's timemachine ;-)

  From DaDaDom