RAID ?? Can You use a independent HD for your system Disk with RAID Array for Data?

[Fly'n_Blind!]

Guys,

Is it possible to use a separate hard disk for your OS and programs with data storage on a RAID Array consisting of two (or more) identical hard disks?

Would the system disk need to be the same size as the disks used for the RAID Array?

Thanks!

Fly'n_Blind!