Will the Fusion Drive assemble, what is the size of the SSD?

Question

Hard disks

I was finally going to install ssd in macbook . I'm going to leave the old hdd, replacing the drive.
Questions:
1) Fusion Drive will assemble on its own, or will you have to conjure (complete data loss is not critical - everything is scattered in the clouds)
2) How much ssd should I take? If you estimate that the system will take even 20GB + browser, photoshop, phpstorm, maybe a couple of toys - it turns out to be 60GB to the eyeballs. In general, is this normal, or is it still better than 120?

Answer 1

It is better to take an ssd with a margin. When the threshold is set to 60% of the occupied space, they wear out faster.

Answer 2

Better than 120. And even better - 240.
Fusion Drive is not assembled on its own (on a live system), but it is converted by hand step by step normally (at 10.9). Wash - with just one reboot. On Habré there was an article on how to assemble Fusion Drive on 10.9 without losing data.