I mentioned non-destructive partitioning only because I know grelber's initial El Cap(?) Time Machine backup is the only data on his new drive, so even if it goes bad, he won't lose much, but knowing his attitude towards such things, I shouldn't have even mentioned it.

Originally Posted By: joemike
All the existing data on the drive will be placed in the first partition. and some versions of OS X/MacOS are not bootable unless they are on the first partition of a drive.

Wow! I haven't heard that caveat since the very early days of OS X, and I wasn't even aware that it was still "live".

I can say, however, that I've booted (at the least) Snowy, Yosemite, El Cap, and Sierra from the third partition of my internal HD/SSD and High Sierra (at the least) from the fourth partition of my external SSD, so I doubt that grelber will have a problem if he puts TM on partition 1 and his clone on partition 2.

The important thing, though, is that the two should, probably even must, be on separate partitions.

The new Great Equalizer is the SEND button.

In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire