Crucial's nomenclature suggests that we're dealing with a pared-down version of the company's 2.5" m4. The mSATA-based family is available in 32, 64, 128, and 256 GB capacities, though we're only testing the three largest models today, and probably wouldn't recommend bothering with a 32 GB drive anyway. That's barely large enough for a 64-bit Windows 7 or 8 installation, which eats up more than 20 GB on its own.
Crucial's m4s with mSATA interfaces employ the same eight-channel Marvell 88SS9174 controller found on the company's older and more familiar 2.5" models. The company also uses the same 25 nm NAND from IMFT. As you can see, though, there is only room for four BGA memory packages on the diminutive PCB. So, some of the same interleaving issues that affected Adata's XPG SX300 drives are bound to surface when we compare lower-capacity drives to the larger models with more flash.
Random read performance is consistent from a queue depth of one all the way through 32, with the 256 GB m4 trailing just slightly. This is in contrast to what we saw from Adata's drives, which were clearly differentiated by the time we hit higher queue depths.
Without the benefit of DuraWrite, a SandForce-only technology, Crucial's m4s behave a lot like Adata's XPG SX300s faced with incompressible data. They all turn in similar numbers at a queue depth of one in our 4 KB random write test. At a queue depth of two, the 128 and 256 GB models stand apart from the 64 GB drive. And by the time we push a queue depth of four, the 256 GB sits atop Crucial's stack.
It takes a queue depth higher than four for the 64 and 128 GB m4s to catch up to Crucial's 256 GB model, though, at several other points in the chart, all drives perform similarly in our 128 KB sequential read test.
DuraWrite helped Adata's XPG SX300s maintain comparable transfer rates in our 128 KB sequential write benchmark, so long as data was compressible. As soon as the SandForce-powered SSDs were faced with incompressible data, however, we saw clear differences between each capacity level.
It doesn't matter what type of data you throw at Marvell's controller; the m4s don't exhibit that dualistic behavior typical of SandForce-based competition. But right out of the gate we see the 64 GB m4 achieving less than half as much throughput as the 256 GB model, with 128 GB between them.