I’d suggest you post this on the Xsan or San networks forum.
If you are accesing the same media, you will need some type of San somewhere along the line. If you only want to write to one RAID and read the others then you could manage with a volume based SAN such as SanMP
Cheapest way would be:-
1) San in a can solutions such as terrablock
2) Metasan & a fibre channel switch. (File based)
Peter