The Plextor M9Pe NVMe SSD Review: Teaching An Old Chip New Tricks

Conclusion

The past year has seen almost all remaining SSD product lines with MLC NAND switch to 64-layer 3D TLC NAND. This is the only significant hardware change the Plextor M9Pe brings over its predecessor, along with updates to the NVMe 1.3 standard in its controller.

The second-generation Western Digital WD Black SSD showed that Toshiba/SanDisk BiCS 3 64-layer 3D TLC can be very fast, but that performance is not on display with the Plextor M9Pe. The WD Black owes much of its success to Western Digital's new in-house NVMe SSD controller that has replaced the Marvell controller used by the first-generation WD Black. It is that older Marvell controller which powers Plextor's NVMe SSDs, including the M9Pe.

It appears that the Plextor M9Pe is held back by the outdated SSD controller. The Marvell 88SS1093 "Eldora" was one of the first NVMe SSD controllers to hit the market. Until recently, it was also clearly the best M.2-sized controller on the open market, but Silicon Motion's SM2262 controller has now taken that spot. (Samsung and Western Digital have clearly superior controllers for their own SSDs, but they aren't sharing them with other vendors.) Marvell has recently announced the 88SS1098 "Zao" as a successor to the 88SS1093, but it is too late for the first wave of 64L 3D NAND SSDs. With a fourth CPU core, an upgraded LDPC engine, a 50% faster flash interface and support for LPDDR4 DRAM, the 88SS1098 should bring Marvell back into competition, but by the time it is ready, the Phison E12 and Silicon Motion SM2262EN will also be shipping. In the meantime, the 88SS1093 "Eldora" controller needs to be retired.

At Computex next month we hope to get a preview of Plextor's plans for a successor to the M9Pe. It's possible they may have something in the works based on the Phison E12 controller and Toshiba NAND or Silicon Motion SM2262(EN) and Micron NAND, but if they stick with Marvell for their high-end NVMe SSDs, we won't see anything new ship until 2019.

That leaves Plextor with pretty much the slowest flagship SSD of any brand. The M9Pe is consistently behind the Intel 760p, WD Black and Samsung 970 EVO. The Plextor M9Pe can usually match the performance of the MLC-base M8Pe, but on heavier workloads it falls behind. The performance situation isn't all bad: the M9Pe is definitely a step up from entry-level NVMe SSDs like the MyDigitalSSD SBX, and also from the planar TLC-based M8Se. Unlike low-end NVMe SSDs, the M9Pe doesn't have any acute weaknesses where performance drops below that of a decent SATA SSD. Generally speaking, the M9Pe is fast enough that it is hard to notice a difference between it and the top SSDs without breaking out special-purpose storage benchmark software. The M9Pe still manages to qualify as a high-end NVMe SSD, just not the very top tier.

Power efficiency is also a challenge for the M9Pe. It seldom demonstrates much improvement over its predecessors that used planar NAND. From other vendors, we've seen drives in this generation show impressive power efficiency improvements as they move to 64L 3D NAND, and we were hoping to see the same from the M9Pe. Users concerned about power consumption will obviously not be interested in the PCIe add-in card version of the M9Pe with more than 1W of LEDs, but even the bare M.2 module is a poor choice for battery-powered systems.

The big selling points of the M9PeY variant are the adapter card's large heatsink and the RGB LED lighting. The LEDs are purely a matter of taste (or lack thereof), but M.2 cooling solutions are often marketed as having some functional benefit. In our testing, the heatsink didn't make any difference to performance. Even our synthetic benchmarks are designed to focus on conditions representative of real-world client usage, and at low queue depths and for sustained transfers that are limited to just tens of GB at a time, the M9Pe doesn't overheat. Long-running tests that simply read or write continuously at very high queue depths may be able to show the heatsink making a difference after a few minutes, but such a test doesn't say anything about real-world use cases. Even when transferring data to or from another high-end NVMe SSD, it's hard to produce the conditions necessary to overheat the drive: either filesystem overhead slows things down, or you quickly run out of data to transfer.

While even the Samsung 970 EVO would save money and deliver better performance than the M9Pe, the most interesting deals at the moment are on the drives using the Silicon Motion SM2262 controller and Intel/Micron 64L 3D TLC. The Intel SSD 760p's prices are still elevated compared to the launch prices, but the HP EX920 and ADATA SX8200 offer similar performance for much lower prices. In particular, the current sale price of $299.99 for the 1TB EX920 is astounding, and I'm surprised Newegg hasn't sold out of the EX920 in the time it takes me to write this. 

The current pricing of the Plextor M9Pe is unfortunate. The bare M.2 drive is priced slightly higher than the Samsung 970 EVO and WD Black. The heatspreader or add-in card options only drive the price further beyond reasonable. Based on performance and power consumption, the M9Pe should be the second-cheapest drive on this chart, not the most expensive. To some extent, it isn't a surprise that Plextor would have trouble beating the vertically-integrated NAND manufacturers on price, but the HP EX920 and ADATA SX8200 show that it's possible while still budgeting for a high-end controller. Lite-On has enough purchasing power to get NAND at similar prices to ADATA, so I suspect they're simply not trying hard to make the M9Pe price competitve, while they direct most of their NAND supplies to their enterprise and OEM drives. This would explain the spotty availability of the M9Pe, with the 1TB AIC model being unavailable at the moment and the rest only available from Newegg. Either that or they have a customer contract and had no major plans to bring this unit to retail.