you would be throttling down down those 6 G bit SATA drives through a 2 G bit at best Ethernet connection!
The theoretical connection speed of current SATA disks is 6 Gbit/sec, whereas a "standard" gigabit ethernet connection available on all current motherboards is 1 Gbit/sec. Some motherboards have faster gigabit -- 2.5 Gbit/sec up to 10 Gbit/sec. However, neither of these figures corresponds to practical throughput, which is generally lower.Is there a NAS that won't throttle like the one above?
I think that these speeds are mostly irrelevant for domestic users. If you stream a UK HD TV recording from the NAS to view on the HTPC, you need at most around 4 to 5 Mbit/sec (yes, that is Mbit/sec, not Gbit/sec). MP has a "Tuning Details" panel that most MP skins support, and you can see there the bitstream speed of the programme that you are currently viewing. Some skins display this value on the OSD too.
Also, how will your NAS be connected to your HTPC and the other devices on your home network? If you are using powerline network adapters, their speed is much lower than gigabit, even if the adapter is specified as "gigabit". On my powerline network using gigabit everywhere, the practical throughput is around 220 Mbit/sec.
-- from CyberSimian in the UK