You want a drive at least as large or larger than the drive you are going to be using the Time Machine drive for." In my case, I think that's overkill, right? My Macbook holds 500 GB. I didn't quite understand all that you said, but as long as I get an external drive of at least 150 GB, I think I will be safe from what I've deduced. Also, if I get crazy with it, I can always buy a larger capacity hard drive.
That is the standard advice for Time Machine drives straight from Apple. I have used Time Machine since it was first available and IMO that is good advice. While you have never had a drive failure, hard drives are the single most failure prone part of any computer system. Tacit was right on in his previous post in this thread where he said...
There are two kinds of computer users in the world: those who have experienced a catastrophic loss of their hard drive, and those who will
It is not a matter of
IF you will have a hard drive failure — it is a question of
WHEN.
