When my Mac (10.5.7) runs the weekly automatic back-up to external HD, can I do other things at the same time?

Yup.. Not a problem.

@johnpowell: If you weren’t here to tell me this, is there somewhere I could search? I really would like to learn more.

http://shirt-pocket.com/forums/ They make the program SuperDuper!. It is what I use for back-ups. You could ask over there if you want specifics. Or just search around.

Yup. I wouldn’t necessarily copy other files back and forth from that drive, but that’s probably because I’m paranoid. Most things, if not all things, should be fine.

It’ll be fine. The Apple support discussion community is a great place for help from those in the trenches: http://discussions.apple.com/index.jspa

@johnpowell: Well, I am smarter than I thought. I use DuperDuper for back-up from Time Machine. It might be a good idea to read the manual, after I’ve read the one for my camera, and my many other gadgets. They’re all written in twenty languages, but unfortunately not Finnish.

Thank you, all. I too am paranoid now that things are running so beautifully on Leopard. When Snow Leopard arrives in Sept., I’ll be back.

@gailcalled, I suggest taking some items into consideration. The purpose of the weekly backup is to make a complete snapshot of the system in case of catastrophe.

For certain heavy-duty apps with an internal database behind the scenes, if you’re in there working while the weekly snapshot is going on, then you might find certain items are out-of-sync where the backed-up copy of the database says one thing, but certain other elements reflect a newer status.

So, what would those heavy-duty apps be? I’m thinking Apple Mail (or Thunderbird), iTunes (just don’t import), iPhoto, and similar items.

It would be totally fine for you to surf the web, visit Fluther, use web-based email (like gmail), etc. If you so choose, you can also elect to edit documents and the like in Microsoft Office or Apple iWork as those are usually discrete items not tied to a set of hidden metadata.

Just my $0.02.

@All; It may be Rob’s two cents, but my guru charges $100 for an hour house visit. And boy, is he busy. So, thank you, fluther.

I would just use the built in Time Machine. Gives you hourly backups that are pretty much seamless.

@All: Follow-up; my SuperDuper just did its weekly automatic back-up from Time Machine. Lo and behold, I could, indeed, surf, read and compose email and visit Fluther. Nothing blew up.

Thanks again, everyone. Theory has become reality.

@jonklein611, Time Machine has its uses – I’m a big proponent! – but it’s not the end-all, be-all of backup strategy. It is simply fantastic at helping the user recover files inadvertently lost or deleted or changed.

However, making a mirror image of your drive on a regular basis is a huge timesaver in case of extreme loss and beats having to rebuild a drive using Apple’s OS X install disk + Time Machine. Further, keeping a mirror offsite is a wise move in case a flood/tornado/fire/hurricane/lightning hits your home.

@robmandu: I have hard copies of everthing I value. And did wonder whether Time Machine deletes junk when I do. Or does it simly expand forever? And then explode?

Time Machine expands to fill the space on the drive/partition you assigned it to.

If your main drive is 250GB, then Time Machine requires you to have a drive for it of equal or greater size. So, if you bought a 500GB external drive for Time Machine, then after a while, you would find that eventually all 500GB are used.

But no, it won’t explode at that point. It just does regular housekeeping and deletes the oldest stuff off in order to make room for newer.

Off the top of my head, I believe Time Machine keeps hourly backups of all your stuff for a day, daily backups for a week, weekly backups for a month. And keeps as much of all that it can on the space available.

BTW, if you’re dead-set serious on keeping hard copies of everything, I suggest reading this.

Turns out that you can store about 180KB of data on a single sheet of paper that’s both encrypted (safe from prying eyes) and provides error correction (the whole can be recovered from only a part, protecting you from fire damage or spilled ink or Milo).