“Please back up your work…” At the moment He is whispering very loudly in the form of my computer claiming (bogusly, I think) that the “disk is full” and refusing to open documents, or, if I trick it into opening them, refusing to save them when I’m done with them. In general, I like my iBook soooo much better than I ever liked any PC I ever owned. I won’t enumerate the reasons here. But, certain things remain confusing, like the mysterious internal organization of programs like iPhoto and iTunes, which have libraries separate from the actual files and seem to sometimes have multiple copies of the same thing, and I really, really don’t know why. And then there’s this odd phenomenon called “Volumes” which appears inside my Finder when I click on Macintosh HD, and appears to be a replica of everything inside my computer, except not a replica. I don’t know what it’s there for. I really don’t.If my disk really is full, do I need to get a second external harddrive, one for everyday use and another to be my “back up” disk? What are the best strategies for effective information storage and retrieval? How do I make sure everything ends up organized and saved in the right places, but nowhere else? I am trying to stay really, really calm about this, and almost succeeding.