Who Needs SATA Express? Six Neutron GTXes in RAID 0

While the M.2 interface has plenty to recommend it, specifically PCIe connectivity in a smaller form factor, SATA Express unfortunately seems to be a lot more underwhelming. The underpinnings are the same (typically two lanes of PCIe) but you sacrifice two SATA ports on your motherboard to use it. You get a theoretical 10Gb/sec of bandwidth for your drive, which is definitely an improvement on SATA’s 6Gb/sec…but if you put two drives in a striped RAID on those same two SATA ports, your theoretical bandwidth jumps up to 12Gb/sec.

And you can still scale.

For a thought experiment, for funsies, we grabbed six of our Neutron GTX 480GB SSDs and tested them in striped RAID from one drive all the way up to all six. We wanted to see where scaling would level off, and just how much performance you could get from going this route. Note that most M.2/SATA Express implementations will be limited to an effective ~850MB/sec after overhead is taken into account. In terms of pure theoretical performance, even two conventional SATA SSDs in RAID 0 should be able to meet or beat that bar.

The testbed employed an Intel Core i7-4770K @ 4GHz, 8GB of DDR3-2133, and Intel’s Z87 chipset. The system drive was connected to a separate ASMedia SATA controller, allowing all six of Intel’s SATA 6Gbps ports to be used in the array.

The benchmark AS SSD shows fairly steady gains in read and write performance and seems to plateau at about four drives. You’ll see this as a trend moving forward; two drives can easily match what SATA Express can do, and then moving past that is just gravy. Interestingly, write performance temporarily surpasses reads at three or four drives, but this is isolated to AS SSD.

ATTO tends to produce the absolute best case scenarios. Our testing shows scaling essentially petering out at the fourth drive, just like AS SSD does. The numbers are impressive, though; just two drives can offer a staggering gigabyte-per-second of read speed, and it only gets faster when you add more.

Crystal Disk Mark again plateaus at four drives. Two drives again meet or beat SATA Express, while three drives start to reach beyond it and four drives are mind-bogglingly fast.

Finally, IOMeter’s 4K random read and write benchmarks (we’ve been largely sequential up until this point) are brutal, but enlightening. Interestingly, 4K performance flattens out on the third drive instead of the fourth. The amount of operations these drives running in parallel can perform is pretty impressive, though.

Users aching for faster storage than even a single conventional SSD can provide (and that’s a pretty fast experience in and of itself) will be heartened to see Intel’s chipset can scale reasonably well up to four drives and even eke at least a little more out of the last two.