ethyr2000

I have a 20 SAS drive array w/ 6gbps controller. I'd like to mix drives. And I've noticed dimmless SSD are cheap. I know the concern is writes and write speed. If I were to use this for movies (practically write once) and upload to cache to have the system place later. This home system will be idle most of the time. Will the slower rate of one drive in it's own pool affect the rest on the controller?

The system I'm building has an external sas controller and an internal sata controller. Since my data storage is going to be on the sas controller, which controller works best for the parity drives?