Plextor M6S 256GB SSD Review

Plextor hits back with a mainstream SSD that's optimized for low power and gives end-users more performance than the previous generation M5S.

Published   |   Updated Tue, Nov 3 2020 7:00 PM CST
Manufacturer: Plextor
10 minute read time

Introduction & Specifications, Pricing and Availability

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For the last several years, Plextor has used a two-tier strategy for its SSD products. We've already tested Plextor's flagship SSD for 2014, which is the M6e. The M6e uses a PCIe interface via M.2 and an adapter card. Today, we have the M6S, Plextor's 2014 mainstream offering, on the test bench.

The M6S is noticeably faster than last year's mainstream M5S SSD. In some cases, it's even faster than the M5 Pro and M5 Xtreme products. The drive uses a new Marvell 4-channel controller that's designed to provide smooth performance while consuming significantly less power than enthusiast class SSDs and hard drives. The drive also uses Toshiba toggle mode flash like its predecessors.

Any SSD buying decision starts by looking at prices. This is where Plextor needs to be competitive once the initial MSRP falls off. With new low cost, high performance products on the market from ADATA and Crucial and 1y flash on the way from Flash Forward (Toshiba and SanDisk flash), SSDs are headed to new price points that are much lower than 2013 prices.

Specifications, Pricing and Availability

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The M5S product family consists of three capacity sizes: 128GB, 256GB, and 512GB. This is the first product we've tested with the new Marvell 88SS9188 4-channel controller. Plextor paired the new controller with 19nm Toshiba toggle mode NAND flash. The 256GB model we're testing today has a 256MB DDR3-1600 buffer for page data.

This combination delivers 520 MB/s sequential reads and 420 MB/s sequential writes on our 256GB sample. The write speed varies between each model. The 128GB drops to just 300 MB/s sequential writes, but the 512GB model increases to 440 MB/s.

Random IOPS performance changes between the three models as you can see in the chart above. The 256GB drive we're testing today delivers up to 90k IOPS read and 80k IOPS write at queue depth 32.

Plextor covers the M6S with a three-year warranty, but the drives do not ship with an elaborate accessory package. It's an odd position to have at this time with MSRPs as high as the Plextor positioned the M6S at. The 128GB has an MSRP of $139.99, the 256GB is $249.99, and the 512GB model is $499.99.

Plextor M6S 256GB SSD

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With the M6e and now the M6S, it looks like Plextor is tuning its image with new product packaging colors and designs.

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Inside, we found that the M6S is slim on accessories. We found the drive and instruction manual.

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Here we get our first look at the actual drive.

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The serial, model, and part numbers are all on the back of the drive.

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The M6S is a 2.5-inch, 7mm z-height design, so it will fit in your ultra slim Ultrabook.

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All of the components are on this side of the PCB. We only have the 256GB model on hand, so we can't speak about the layout on the 128GB or the 512GB drives. The 256GB M6S uses eight Toshiba TSOP Toggle NAND flash packages and a single DRAM package.

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The controller is new from Marvell, and this is the first time we've tested it. The model number is SS889188, and Plextor uses it on both the M6S and M6M, an mSATA variant.

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Plextor used DDR3 running at 800MHz (1600HMz effective) for the buffer. The package uses just 1.35 volts on the sample we received with Micron DRAM. A picture surfaced online in Asia with an SK Hynix DRAM package, so Plextor may interchange the components.

Test System Setup and ATTO Baseline Performance

Desktop Test System

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Lenovo W530 - Mobile Workstation

We use two systems for SSD testing. The desktop runs a majority of the tests, and the Lenovo W530 runs the notebook power tests as well as the real-world file transfer benchmark.

ATTO - Baseline Performance

Version and / or Patch Used: 2.34

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In ATTO, we achieved just over 521 MB/s sequential read and 446 MB/s sequential write speeds. These are in line with Plextor's advertised speeds on the specifications document released to the public.

Benchmarks - Sequential Performance

HD Tune Pro - Sequential Performance

Version and / or Patch Used: 4.55

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For a 4-channel controller, the Plextor M6S performs very well. In HD Tune Pro, the 64KB sequential read averaged 450 MB/s, and the performance stays steady when reading the data.

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The single pass 64KB sequential write speed averaged 354 MB/s, but this is on a fresh drive.

HD Tach - Sequential Write Performance after Random Writes

Version and / or Patch Used:

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Things change a bit after a reasonable amount of random writes to the drive. HD Tach uses 128KB for the sequential read and write test. Here we see the reads holding strong near 425 MB/s, but the sequential writes drop halfway through the test. There are also two reverse spikes in the test, one getting as low as 20 MB/s. The second half of the test shows a large reduction in sequential write performance similar to what we see on Toshiba and OCZ branded SSDs.

Benchmarks - Anvil Storage Utilities

Anvil Storage Utilities

Version and / or Patch Used: RC6

So what is Anvil Storage Utilities? First of all, it's a storage benchmark for SSDs and HDDs where you can check and monitor your performance. The Standard Storage Benchmark performs a series of tests; you can run a full test or just the read or the write test, or you can run a single test, i.e. 4k QD16.

Anvil Storage Utilities is not officially available yet, but we've been playing with the beta for several months now. The author, Anvil on several international forums, has been updating the software steadily and is adding new features every couple of months.

The software can be used several different ways to show different aspects for each drive. We've chosen to use this software to show the performance of a drive with two different data sets. The first is with compressible data, and the second data set is incompressible data. Several users have requested this data in our SSD reviews.

0-Fill Compressible Data

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Incompressible Data

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The Plextor M6S works with both compressible and incompressible data the same way, so performance stays the same regardless of data type.

Read IOPS through Queue Depth Scale

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The low queue depth IOPS performance is very good. At QD1, we achieved just under 9400 IOPS. The M6S scales well, going from just over 17k IOPS at QD2 to tipping the scales at nearly 95k IOPS at QD32.

Scaling Write IOPS through Queue Scale

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The M6S 4k write IOPS performance is faster than the M5P Xtreme but below some of the newer drives on the chart. We're actually quite surprised to see this level of performance from the Marvell 88SS9188 controller given its 4-channel design. At the high-end of the scale, the M6S nearly hits 84k IOPS.

Benchmarks - PCMark Vantage (Drives with Data Testing)

PCMark Vantage - Drives with Data Testing

Version and / or Patch Used: 1.0.0

For a complete breakdown on the Drives with Data Testing, please read this article. You will be able to perform this test at home with the files provided in the article; full instructions are included.

Brief Methodology

SSDs perform differently when used for a period of time and when data is already present on the drive. The purpose of the Drives with Data testing is to show how a drive performs in these 'dirty' states. SSDs also need time to recover, either with TRIM or onboard garbage collection methods.

Drives with Data Testing - 25%, 50%, 75% Full States and Dirty / Empty Test

Files needed for 60 (64GB), 120 (128GB), 240 (256GB)

60GB Fill - 15GB, 30GB, 45GB

120GB Fill - 30GB, 60GB, 90GB

240GB Fill - 60GB, 120GB, 160GB

Empty but Dirty - a test run just after the fill tests and shows if a drive needs time to recover or if performance is instantly restored.

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In PCMark Vantage, we hit just over 90k Marks with the drive lightly used. With 50 percent of the flash occupied with data, the performance dropped to 44k Marks but quickly returned to nearly 86k Marks in the TRIM test after we deleted the data on the drive.

The 50 percent mark is what we like to use to measure performance reduction on the drives. The M6S is faster than several other drives on the chart, especially those in the mainstream budget category. The M6S is also faster than the M5P Xtreme we tested last year.

PCMark 8 Consistency Test

Futuremark PCMark 8 Extended - Consistency Test

Version and / or Patch Used: 2.0.228

Heavy Usage Model:

FutureMark's PCMark 8 allows us to wear the test drive down to a reasonable consumer steady state and then watch the drive recover on its own through garbage collection. To do that, the drive gets pushed down to steady state with random writes and then idle time between a number of tests allows the drive to recover.

Precondition Phase:

1. Write to the drive sequentially through up to the reported capacity with random data.

2. Write the drive through a second time (to take care of overprovisioning).

Degradation Phase:

1. Run writes of random size between 8*512 and 2048*512 bytes on random offsets for 10 minutes.

2. Run performance test (one pass only).

3. Repeat 1 and 2 for 8 times, and on each pass increase the duration of random writes by 5 minutes.

Steady state Phase:

1. Run writes of random size between 8*512 and 2048*512 bytes on random offsets for 50 minutes.

2. Run performance test (one pass only).

3. Repeat 1 and 2 for 5 times.

Recovery Phase:

1. Idle for 5 minutes.

2. Run performance test (one pass only).

3. Repeat 1 and 2 for 5 times.

Storage Bandwidth

PCMark 8's Consistency test provides many data outputs that we use to judge a drive's performance.

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We're starting with the throughput in worst case (blue) and recovery (orange) phases. The worst case performance shows the drives after being hammered with a heavy load, and the recovery phase shows typical performance when you are surfing the web, writing reviews and so on.

The drives are listed in alphabetical order, so you have to go down a few spaces to find the M6S 256GB. Here we see where the 4-channel design hurts the M6S: after a massive workload. Most regular users will never get the drive to this point. The TRIM bandwidth shows the performance in the same tests after periods of light workload and idle time. This represents the performance level most users will encounter.

Disk Busy Time

Disk Busy Time shows us how long the drive has to work to achieve the performance from the above. The best scenario is high throughput performance with low busy time. The less the drive works, the less power it consumes. For the most part, this is an efficiency test.

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The M6S doesn't reserve space for overprovisioning, so it's not as efficient as some of the other drives on the market.

PCMark 8 Consistency Test - Continued

Total Access Time

The access time test measures the total latency across all 18 tests. This is one of the, if not the most, important tests we run at this time for consumer SSDs. When your latency is low, your computer feels fast; it's just that simple.

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We talk about latency quite a bit and have a new test in the works now that shows read and write latency over a period in real-time. Until that test is ready, we have to rely on PCMark 8's access time results. This is the total read and write access time over the entire test. Lower is better for the user experience.

Data Written

In the final test, we measure the amount of data written to the drive prior to the steady state test. The drive is under a constant random write load for 220 minutes. Overprovisioning helps quite a bit here as it allows the drive room to keep some flash clean and ready.

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The M6S 256GB is in the middle of the pack of products we've already ran this test on. The write performance drop we observed in HD Tach shows in this test as the write performance drops under heavy workloads.

Benchmarks - DiskBench

DiskBench - Directory Copy

Version and / or Patch Used:

Note: In this test, we use the Lenovo W530 Mobile Workstation and a SuperSpeed S301 SLC 128GB SSD to move a 15GB block of data to and from the target drive. This is part of our real-world test regiment. Roughly 45GB of data resides on the target drive before the '15GB Block' is transferred. The 15GB Block is the same data we built for the Data on Disk Testing and is a mix of compressible and incompressible data.

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Over the last few months, we've noticed several manufacturers increasing the aggressiveness of the garbage collection scheme. Plextor has always used aggressive GC, but it seems the new Marvell controllers, both 4- and 8-channel, handle this a bit differently.

In our tests, we use the same amount of time between each test for all of the drives. Sometimes this works out well and sometimes we find abnormalities in performance. When background garbage collection is working, the write performance drops. Normally a drive sees data coming in and suspends background GC. If space is needed right away, foreground garbage collection kicks in to clean up the flash.

We see this happening when recording power during a trace test. It seems the new Marvell controllers used in the M6S, ADATA SP920, and Crucial M550 are not suspending the background GC. Write performance can drop when transferring files to the drive if other write operations preceded the transfer. We'll talk about this more on the next page.

Benchmarks - Power Testing & Final Thoughts

Bapco MobileMark

Version and / or Patch Used: 2012 1.5

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The Plextor M6S scored in the middle of the pack in our notebook battery life test at just over 268 minutes on our Lenovo W530 with a six-cell battery.

PCMark 8 - Trace Based Power Testing

Version and / or Patch Used: 2.0.228

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It's been several months since we published this type of power test. When we changed over to Windows 8, our driver had an issue so we moved the data logging meter to another system that uses Windows 7. At the same time, we moved over to PCMark 8 for the test. The one power state we cannot see in this test is DEVSLP since we have low power states disabled on the system to increase performance.

Final Thoughts

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Plextor has a strong relationship with Toshiba, the NAND flash manufacturer for the M6S. Having a relationship and owning a fab are still two completely different things. If Plextor is able to get the TSOP toggle flash cheap enough, then the M6S has a chance of being your next SSD. Flash is the most expensive component in a consumer SSD, so the price of flash plays a significant role in the product cost.

Plextor's MSRP for the M6S products is almost laughable in 2014 for a mainstream SSD offering. Just days before the product launch, Plextor sent over the MSRP information. The 256GB model we reviewed today costs $249.99. That's higher than the Intel 730 enthusiast SSD (Newegg $229.99) and higher than the new Crucial M550 (Newegg $168.99) with an 8-channel controller that offers higher performance.

Performance wise, the M6S doesn't blow the doors of other products on the market, but it's not designed to take on the high-end, enthusiast class SSDs. As a mainstream SSD with a low price point, the drive is good, but the line between mainstream and performance SSDs is currently blurred. Mainstream SSDs are now capable of delivering high IOPS performance, even at low queue depths.

The M6S employs DEVSLP (dev sleep) for very low power consumption at idle. The drive doesn't use a lot of power under load either. Aside from DEVSLP, the M6S also supports hardware encryption for TCG Opal and eDrive. The accessory package is very thin, though, as is the average three-year warranty for this price point. We can only hope the e-tail prices are around half of the MSRP.

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