I needed to
backup the contents of a file sharing directory of a server in our LAN to the shiny new mirrored 1 TB RAID inside my Mac Pro. Having a simple backup is nice, but it's even better to have snapshots, with the possibility to jump back to any date and have the exact representation of the disk as it was back then (TimeMachine also does this pretty well for Macs).
Always creating a complete backup would be a waste of disk space par excellence and in my case - backup via LAN - also pretty hard on the network. Fortunately there is
rsync, and there's our friends
ssh and
launchd. rsync takes advantage of *NIX file system hardlinks and when called with the right arguments only backs up new files since the last backup, pointing to the older copy of a file if the file has not changed in the meantime.
Mike Rubel has written up a nice article covering these aspects of rsync,
check it out.
Rafael: Thank you very much, I was having a huge headache to solve the very same problem!