Plextor is probably best known for its optical storage products such as DVD and Blu-ray drives, but with the M2S solid-state drive series, it looks intent on making a name in SSD storage too.
The Plextor PX-256M2S is one of three models offered. With its 256GB capacity, it sits at the top of the range, with 64GB and 128GB versions also available.
This is a highly specified line of SSD devices, boasting write speeds up to 480MBps and reads up to 330MBps. To achieve that kind of thoughput, it makes use of the latest generation of Serial ATA interface, SATA 6Gbps.
But note that those nominal speeds are only applicable to the highest capacity 256GB drive: looking at the more affordable 64GB drive, we see specifications of ‘up to 370MBps’ and ‘up to 110MBps’ for reads and writes, respectively.
To help keep the pace, the drives feature 128MB of DDR3 RAM cache, and in charge of the drive is a Marvell 88SS9174 controller chip.
With those specs, we see a certain amount of overlap with the PCA Award-winning Crucial RealSSD C300 256GB, and were thus especially intrigued to see how the drives would compare in performance.
The drive itself is built into a smart aluminium case, sized to fit into any space designed for the standard 2.5in notebook hard-disk drive. At 72g, it’s about a third lighter than a comparable 2.5in disk drive.
Benchmarking SSDs is still something of an inexact science: unlike hard-disk technology which allows good levels of consistency and repeatablility, SSDs will alter their performance with normal use and wear.
Features such as trim (undertaken by the computer’s OS), and garbage collection and wear-levelling (supervised by the drive’s controller chip) are employed to help keep these drives in consistent good health. But nevertheless, there is some variability in results, witnessed simply by serially repeating the same benchmark performance tests.
And so it was that we could replicate some of Plextor’s results with certain tests on the Plextor PX-256M2S, while different results were found with other benchmark tools.
For example, we confirmed the headline speed ‘drag-race’ result using the venerable ATTO Bench test.
Here we saw a maximum read speed of 483MBps (in the 512kB transfer size test), and maximum write speeds of 339MBps (by cherry-picking the 32kB result). Whatever way you cut it, those are mightily impressive results.
Turning to more modern test tools, we can see not just the maximum sequential speeds, but telling measurements of stacked-up small file transfers and input/output operations per second (IOPS).
In the CrystalDiskMark test, we saw headline figures of 436 and 320MBps for read and write speeds of random data. For 4kB data though, these speeds dropped considerably, to 17 and 45MBps. And using the 4K QD32 setting, we saw speeds of 69 and 47MBps.
To give some context here, we retested the Crucial RealSSD on the same PC workstation, a newly built test rig customised for such test work.
The Crucial had ATTO read/write figures of 350 and 238MBps, and comparable figures in the CDM benchmark too – all some way behind the Plextor PX-256M2S.
But turning to the small file transfers, the Crucial was around twice as fast: 33 and 86MBps for 4kB files. In the 4K QD 32 test, the Crucial was far ahead, recording read/writes here at 244 and 204MBps.
We used the AS SSD benchmark to get an idea of IOPS performance. Here the Crucial RealSSD showed rounded figures of 56,000 and 45,000 IOPS in the 4K 64-thread test. Turning to the Plextor, the PX-256M2S could only muster around 17,000 and 11,000 IOPS in its read-write cycles.
Adjusting the CDM app to write a string of zeros to the drive, speeds of the Plextor PX-256M2S were roughly similar at 447 and 333MBps respectively, with small-file transfers even closer to the random-data results.
This suggests that the Marvell controller is not attempting to compress/decompress data on the fly to bolster its performance figures, as we have seen in SSDs using some other controllers.