I had the need for a simple backup solution for disk-to-disk backups on servers. I wanted it to be administered through a terminal (via ssh), run in the background without user interaction, and email me a report once it did its work. I also wanted it to autorotate my backups, and to use hardlinks to save space and speed up incremental backups. Since I couldn't find something simple that suited my needs, I wrote mlbackup.
mlbackup is a convenient wrapper around rsync 3, which is included in the download. rsync 3 itself is compiled as an universal binary, optimized for PPC and Intel processors in 32-bit and 64-bit incarnations.
There are a ton of features in mlbackup; beyond the autorotation, use of hard links, and email notification noted above, it also includes easy configuration via a text file, backs up all HFS+ metadata, skips certain OS X files (caches, temp files) that don't need to be backed up, and postpones Spotlight indexing until the backup is completed. It can also be used to remotely pull backups with rsync ssh transport. (This requires ssh hostkey authentication to be set up for automated backups.) For this to work, mlbackup needs to be installed on both source and destination Macs, and having the same version installed across Macs is highly recommended!
mlbackup is available for free under the GPLv3, and all sources are included with the download. Bugreports and feedback for mlbackup are welcome; the email address can be found in the README file included in the download. Backups created with mlbackup pass the backup tests in the Backup-Bouncer test suite.
[robg adds: I found this worth mentioning because I've basically cobbled together a series of scripts that do similar things, but each one needs to be customized for the backup task at hand, and I know I don't copy all the proper HFS+ metadata. While I haven't tested mlbackup yet, I intend to -- and given that it's free and open source, I thought others might be interested as well. I have mirrored the r88 download (2MB) here on Mac OS X Hints, in case the original server isn't available at some point in the future. You should check the author's site first for the latest version, however.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20080907075415331