I'm considering to build one with something like this: http://www.supermicro.com/products/chassis/4U/847/SC847E26-R1400U.cfm (a chasis with two dual port multipath expanders) http://www.supermicro.com/products/accessories/addon/AOC-SAS2LP-MV8.cfm (4 8-port plain SAS controllers, 2 for each backplane) and 36 Seagate 3Tb SAS drives (ST33000650SS) OS -- FreeBSD. And it's very interesting: How good expander sas backplanes and multipath configurations work with freebsd ? How to locate a specific drive in the bay? (literally -- how to blink an indicator on the drive in freebsd) How to detect a fail of a controller? Will it work together at all? I'm asking to share any experience.