Francine I run 3 Lacie Porsche backup drive using Lacie software SilverKeeper and I backup my other 5 drives with it too.
I noticed you wanted to know what basic files were needed to boot. I hope you don't just boot to a minimal drive? The best reason for a bootable backups is to secure the data you have on your internal drive.
My backup plan consisted of using drives that could be installed into my Macs if the original failed. The Porsche style use Western Digital notebook drives that I can swap out with either iBook or eMac without loosing data or time.
Now that you have a good idea about bootable backups, create a plan that will secure your data to suit your needs. I set my backup software to automatically turn on once a day, and keep email on my server for seven days. If my computer fails I can recover everything except work done between backups and all my incoming email is secure on an external mail-server.
I'm not sure if I can set the backup software to work automatically. I used CCC to make the backups, and I'll have to take a thorough look at the version of Silverkeeper that came with my Lacie. I bought it about 3 years ago, if I'm not mistaken.
BTW I did not backup a minimal drive, partly b/c I didn't know what was essential and what was not. I made my HD lean and mean before upgrading to OS X, and then I backed up pretty much the entire list of what showed up in the CCC window. I also burned a couple of nonbootable CDs of what
looked like essential files, and of all of my documents. I'd like to learn to set up an automatic backup, but so far I have been really good about backing up every month or so. For me, this has been OK because I don't really have all that much stuff on my HD. What I would miss losing the most is stuff I've written, and of my research materials and PowerPoint experiments, and I almost always print a hard copy. I also have a habit of mailing these documents to my Yahoo address, so they're backed up online as well.
Cheers,
Francine