Some backup software is published by individuals who like to program in their spare time. At the other end of the spectrum, some backup software is published by large corporations with a small army of programmers and a full-time, paid technical support staff. Ironically, I've often received better and quicker technical support from individual authorseven those who give away their applications for freethan big companies. On the other hand, if you're entrusting all the data on the computers in your home or small office to a backup application, you may feel more comfortable knowing that a professional staff stands behind the product.
Rolling Your Own with Unix Utilities
Since backups are essentially a matter of copying files, many industrious Mac users have chosen to wrap up a few Unix commands in a shell script (with or without a nice Aqua interface) and call it a backup program. Under Tiger, Apple's included command-line tools (such as cp and tar) have the capability of copying files with both data forks and resource forks intact; under Panther, Apple's ditto tool serves this purpose (see the Glossary for info on data and resource forks). Third-party tools, such as rsync, can do the same, and with proper use, these tools can also maintain the correct creator, type, owner, and permissions settings. Certainly a clever programmer can add a bit of logic to a shell script, employ cron or even iCal to schedule unattended operation, and perhaps use AppleScript Studio to provide a friendly user interface. Indeed, several of the utilities listed in Appendix B were created using this technique.
If you're handy with Unix and want to attempt such an undertaking yourself strictly for fun or as a programming exercise, more power to you. But if your motivation is to save money, I urge you to reconsider. The complex issues one must address in designing backup and restoration routinesparticularly for proper additive incremental archiveswill take many hours to work out in even a rudimentary way. Even if you think your time is worth only a few dollars an hour, you'll save yourself both money and grief by purchasing a ready-made backup application.
For one example of a way to use rsync for backups, see Richard Hough's article "Automated Backups on Tiger Using rsync" at O'Reilly's MacDevCenter.com (www.macdevcenter.com/pub/a/mac/2005/07/22/backup.html).
But remember that such a strategy is less sophisticated than what most backup applications can offerand it comes without any technical support!
Of special note in this regard is EMC Insignia, developers of Retrospect. They charge $70 to speak to a technical support representative on the phonea seemingly outrageous fee. However, I've used technical support from Dantz (which was purchased by EMC) more than once, and I believe you get what you pay for. The technicians answer promptly, are highly trained, and continue working with youeven over multiple phone callsuntil the problem is solved (without charging you for each call). When I'm terrified that I might have just lost all my data and my software doesn't seem to be functioning correctly, I'm only too happy to pay $70 for the reassuring voice and advice of an expert who can help me get things working again.