This was the integral part of a fileserver I purchased and assembled February this year. In its initial configuration the machine has eight 1TB drives in a RAID6 array, providing 5.45TB formatted space. Both the 3U chassis I went with (Norco RPC-3116)...
Supports 16 drives on SATA2 ; Supports RAID6 ; Expandable cache ; Came with all necessary cables ; Very good documentation included ; Easy to navigate firmware menus ; PCI-E 8x
Default bundled cache seems small for the number of drives it supports ; Newegg did not carry the upgraded 1GB cache module at the time of purchase ; Expensive...but if you want a real RAID with real reliability, why cheap out