Your drive configuration seems suboptimal for a NAS, to say the least. Depending on your exact pool setup, you'll be using 8 disks to get no more than 1 TB of storage. The 10k disks would do well for your throughput, but you'll be limited by GbE anyway. It seems you'd spend less money, power, and space in your chassis to buy a pair of 1 TB disks and mirror them. What factors led you to settling on this hardware configuration?