M.2 done wrong
To early adopt or not. That is the question. At least, it’s the question you’d better have in mind when considering the new Plextor M6e. Because it most definitely ain’t the finished M.2 article.
All this M.2 and PCI Express stuff is still quite new and certainly a little confusing, so let’s recap. M.2 is the new PCI Expressbased storage interface that’s taking over planet Earth. Well, it’s taking over the little bit of planet Earth that is PC data storage. In the process it’s replacing the venerable SATA interconnect.
That’s overdue for several reasons. Firstly, SATA development has crept along at what you might call a rather stately pace, requiring a new standard for each and every speed boost. Meanwhile, the underlying performance of solid-state drives has grown fast and thumped firmly into the 6Gbps ceiling of SATA. Make PCI Express the basis of your storage connectivity and you can dial up more bandwidth merely by adding more links. Whoopie.
What’s more, the control protocol that comes with SATA, known as AHCI, is a clunky old thing designed for ratty old magnetic drives. And it simply isn’t any good at talking to sleek, modern SSDs and their zingy NAND memory chips. For that you want NVMe and its low-latency cleverness. Except this M.2 drive from Plextor doesn’t have NVMe support, which is where the early adopter angle comes in. As we’ll see, there are still benefits of an M.2 drive like this that makes do with AHCI, but it’s almost certainly not nearly as good as the NVMe M.2 drives that are due later this year.
We also can’t help but notice that the M6e sports a mere two-lane PCI Express interface. Now it just so happens that Intel limited bandwidth to its native M.2 slots for the H97 and Z97 chipsets to two lanes. So you could argue that’s academic for most right now. But then you could also use this SSD in a PCI Express adaptor card to sidestep that limitation.
What’s more, there’s the Marvell 9183 controller onboard, which bodes well enough, and for this 512GB version you also get a full 1GB of DDR cache memory and a decent five-year warranty. Not bad. Nor are the M6e’s test results. It is unambiguously, undeniably quicker than any SATA drive in sequential work loads, be that synthetic or real world. On the synthetic side, you’re looking at peak data transfer in and around 700MB/s in both directions.
Back in the real world, it zaps our 30GB file transfer test in two minutes and 46 seconds. Most SATA drives take 30 to 40 seconds longer. That, unfortunately, it where the good news ends. No doubt thanks to a controller chipset that doesn’t talk the new NVMe lingo, 4K random access performance is pretty poor, even by SATA standards. Likewise, it’s dead last in our performance endurance test and returns some seriously nasty looking numbers in the degradation part of that test. Just to add insult to injury, Samsung’s M.2 alternative, the XP941, tears the Plextor a new one when it comes to peak sequential performance, cracking the 1GB/s barrier. It also does very well in the performance degradation test. So there’s little doubt which drive is the pick of the early M.2 movers.
Of course, the M6e is also a proper retail product, so a little easier to find. But as we go to press it’s probably not much, if any, cheaper than the Samsung. If you are absolutely committed to going with a pre-NVMe M.2 drive, it’s hard to make the case for the M6e over the Samsung alternative.