He has 24 4TB drives in 4U, but only 16GB of RAM, and a single E3-1230 (quad core) at 3.30GHz, and 4 x 1Gbps networking. I'm not sure what a "RAID-like cache"

He has 24 4TB drives in 4U, but only 16GB of RAM, and a single E3-1230 (quad core) at 3.30GHz, and 4 x 1Gbps networking. I'm not sure what a "RAID-like cache" is. I know what redundancy is, and I know how ZFS works. 16GB is likely adequate for his storage needs. He doesn't have that many clients accessing the storage. and I could keep two complete copies of the data on two machines, each with redundant power, etc.