I'm setting up a raid 5 on a asus h77 mobo with the aim ofIntel RST on 3 2TB WD GREEN disks for the first time.

I'm also considering to buy a 32GB ssd drive for raid cache (flashcache).

but I don't know where to install OS on ?

Plan1: install ubuntu and flashcache on a 64 GB ssd drive ( 32GB ubuntu / 32GB flashcache ) ?

Plan2:use a permanent installation on a USB3 flash and a 32GB ssd raidcache ?

any other advises appreciated