M sata connector. SSD M.2 - Realities of the standard and an overview of the available model Sandisk X300

19.06.2019 Errors

That in the past, that this year, articles about SSD can be safely started with the same passage: "The market for solid-state drives is on the verge of major changes." For several months in a row, we have been looking forward to the moment when manufacturers will finally start releasing fundamentally new models of mass SSD for personal computers, which, instead of the usual SATA 6 Gb / s interface, will use the faster PCI Express bus. But the bright moment, when the market is flooded with fresh and noticeably higher performance solutions, everything is postponed and postponed, mainly due to delays in finishing the necessary controllers. The same single models of consumer SSDs with a PCI Express bus, which are still becoming available, are still clearly experimental in nature and cannot amaze us with their performance.

Being in such an agonizing expectation of change, it is easy to lose sight of other events, which may not have a fundamental impact on the entire industry, but nevertheless are also important and interesting. Something like this happened to us: unnoticed in the consumer SSD market, new trends have spread, which we have hardly paid attention to until now. SSDs of a new format, M.2, began to appear on sale in large quantities. A couple of years ago, this form factor was referred to only as a promising standard, but over the past year and a half, it has managed to gain a huge number of supporters both among platform developers and among SSD manufacturers. As a result, M.2 drives are not a rarity today, but an everyday reality. They are produced by many manufacturers, they are freely sold in stores and are commonly installed in computers. Moreover, the M.2 format has managed to win its place not only in the mobile systems for which it was originally intended. Many desktop motherboards today are also equipped with an M.2 slot, as a result of which such SSDs are actively penetrating into classic desktops as well.

With all this in mind, we've come to the conclusion that we need to pay close attention to M.2 SSDs. Despite the fact that many models of such flash drives are analogs of the usual 2.5-inch SATA SSDs, which are tested by our laboratory on a regular basis, among them there are also original products that do not have twins of the classic form factor. Therefore, we decided to make up for lost time and conduct a single consolidated test of the most popular capacities of 128 and 256 GB available in domestic stores M.2 SSD. The Moscow company “ Regard”Offering an extremely wide range of SSDs, including those in the M.2 form factor.

⇡ Unity and Diversity of the World M.2

M.2 slots and cards (formerly called Next Generation Form Factor - NGFF) were originally developed as a faster and more compact replacement for mSATA, a popular standard used by solid-state drives in various mobile platforms. But unlike its predecessor, the M.2 offers fundamentally greater flexibility in both the logical and the mechanical part. The new standard describes several options for the length and width of cards, and also allows you to use both SATA and the faster PCI Express interface for connecting solid-state drives.

There is no doubt that PCI Express will replace the interfaces we are used to. Direct use of this bus without additional add-ons allows to reduce latency when accessing data, and due to its scalability, it significantly increases throughput. Even two PCI Express 2.0 lanes are capable of providing noticeably higher data transfer rates compared to the usual SATA 6 Gb / s interface, and the M.2 standard allows you to connect to an SSD using up to four PCI Express 3.0 lanes. The foundation for increased throughput, thus laid, will lead to a new generation of high-speed solid-state drives capable of faster loading of the operating system and applications, as well as lower latency when moving large amounts of data.

SSD interface	Maximum theoretical bandwidth	Maximum real throughput (estimate)
SATA III	6 Gbps (750 MB / s)	600 MB / s
PCIe 2.0 x2	8 Gbps (1 Gbps)	800 MB / s
PCIe 2.0 x4	16 Gbps (2 Gbps)	1.6 GB / s
PCIe 3.0 x4	32 Gbps (4 Gbps)	3.2 GB / s

Formally, the M.2 standard is a mobile version of the SATA Express protocol described in the SATA 3.2 specification. However, it turned out that over the past couple of years, M.2 has spread much more widely than SATA Express: M.2 connectors can now be found on current motherboards and laptops, and SSDs in the M.2 form factor are widely available on the market. SATA Express, on the other hand, cannot boast of such support from the industry. This is partly due to the greater flexibility of M.2: depending on the implementation, this interface can be compatible with devices operating on the SATA, PCI Express and even USB 3.0 protocols. Moreover, in its maximum version, M.2 supports up to four PCI Express lanes, while SATA Express connectors are capable of providing data transfer over only two such lines. In other words, today it is M.2 slots that seem to be not only convenient, but also a more promising foundation for future SSDs. Not only are they suitable for both mobile and desktop applications, they are also capable of providing the highest bandwidth available for consumer SSD connectivity.

However, given the fact that the key feature of the M.2 standard is the variety of its types, it should be borne in mind that not all M.2 drives are the same, and their compatibility with different variants of the corresponding slots is a separate story. To begin with, the boards of the solid state drives available on the market in the M.2 form factor are 22 mm wide, but have five lengths: 30, 42, 60, 80 or 110 mm. This dimension is reflected in the marking, for example, the form factor M.2 2280 means that the drive card is 22 mm wide and 80 mm long. For M.2 slots, a complete list of drive card dimensions is usually indicated, with which they can be physically compatible.

The second feature that differentiates the different M.2 variants is the "keys" in the slotted slot and, accordingly, in the knife slot of the cards, which prevent the installation of storage cards into slots that are logically incompatible with them. At the moment, for M.2 SSD, two options for the location of keys are used from the eleven different positions described in the specification. Two more options have found application on WLANs and Bluetooth cards in the M.2 form factor (yes, it happens, for example, the Intel 7260NGW wireless adapter), and seven key positions are reserved for the future.

	M.2 slot with Type B key (Socket 2)	M.2 slot with M key (Socket 3)
Scheme
Key location	Contacts 12-19	Contacts 59-66
Supported interfaces	PCIe x2 and SATA (optional)	PCIe x4 and SATA (optional)

M.2 slots can have only one baffle key, but M.2 cards can have multiple notch keys at once, which will make them compatible with several types of slots at the same time. Type B key, located instead of pins with numbers 12-19, means that no more than two PCI Express lanes are connected to the slot. An M key occupying pins 59-66 means that the slot has four PCI Express lanes and therefore can provide better performance. In other words, the M.2 card must not only fit, but also have a slot-compatible key arrangement. At the same time, the keys not only limit the mechanical compatibility between various connectors and M.2 form factor boards, but also perform another function: their location prevents incorrect installation of drives in the slot.

The information given in the table should help to correctly identify the type of slot available in the system. But it should be borne in mind that the ability to mechanically dock the slot and the connector is only a necessary, but not a sufficient condition for their full logical compatibility. The fact is that slots with keys B and M can contain not only PCI Express, but also SATA, but the location of the keys does not give any information about its absence or presence. The same goes for the M.2 card slots.

	Blade connector with key type B	Blade connector with key type M	Blade connector with keys type B and M
Scheme
Location of the slots	Contacts 12-19	Contacts 59-66	Contacts 12-19 and 59-66
SSD interface	PCIe x2	PCIe x4	PCIe x2, PCIe x4, or SATA
Mechanical compatibility	M.2 slot with type B key	M.2 slot with M key	M.2 slots with Type B or Type M keys
Common SSD models	Not	Samsung XP941 (PCIe x4)	Most M.2 SATA SSD Plextor M6e (PCIe x2)

There is one more problem. It lies in the fact that many motherboard designers ignore the requirements of the specifications and install the "coolest" slots with a type M key on their products, but only two of the four required PCIe lanes are installed on them. In addition, the M.2 slots on motherboards may not be compatible with SATA drives at all. In particular, ASUS is guilty of its love for installing M.2 slots with reduced SATA functionality. SSD manufacturers also adequately respond to these challenges, many of which prefer to make both cut-outs on their cards at once, which makes it possible to physically install drives into M.2 slots of any type.

As a result, it turns out that it is impossible to determine the real capabilities, compatibility and the presence of the SATA interface in the slots and M.2 connectors by only external signs. Therefore, complete information about the implementation features of certain slots and drives can be obtained only from the passport characteristics of a particular device.

Fortunately, the assortment of M.2 drives is not so great at the moment, so the situation did not have time to get completely confused. In fact, there is only one M.2 PCIe x2 model on the market - Plextor M6e - and one PCIe x4 model - Samsung XP941. All other commercially available flash drives in the M.2 form factor use the familiar SATA 6 GB / s protocol. At the same time, all M.2 SSDs found in domestic stores have two cutout keys - in positions B and M. The only exception is Samsung XP941, which has only one key - in position M, but it is not sold in Russia.

However, if your computer or motherboard has an M.2 slot and you plan to fill it with an SSD, there are a few things you need to check first:

Does your system support M.2 SATA SSD, M.2 PCIe SSD, or both?
If the system supports M.2 PCIe drives, how many PCI Express lanes are there on the M.2 slot?
What arrangement of keys on the SSD card allows for the M.2 slot in the system?
What is the maximum length of an M.2 card that can fit into your motherboard?

And only after you can definitely answer all these questions, you can proceed to choosing a suitable SSD model.

Crucial M500

The Crucial M500 M.2 SSD is the equivalent of the familiar 2.5-inch model of the same name. There are no architectural differences between the "large" flash drive and its M.2 sibling, which means that we are dealing with inexpensive SSDs based on the popular Marvell 88SS9187 controller and equipped with 20 nm Micron flash memory with 128 Gigabit cores ... To fit the drive on an M.2 card, which measures only 22x80mm, a tighter layout and flash memory chips with a denser package of MLC NAND dies are used. In other words, Crucial M500 is hardly capable of surprising someone with its hardware design, everything about it is familiar and familiar for a long time.

We received two models for tests - with a capacity of 120 and 240 GB. As in 2.5-inch SSDs, their capacities were somewhat reduced relative to the usual multiples of 16 GB, which means there is a larger spare area, which in this case takes up 13 percent of the total flash memory array. The M.2 versions of the Crucial M500 look like this:

Crucial M500 120GB (CT120M500SSD4)

Crucial M500 240GB (CT120M500SSD4)

Both drives are M.2 cards in 2280 format with B and M keys, which means it can fit into any M.2 slot. Keep in mind, however, that the Crucial M500 (any version) is a SATA 6Gb / s drive, so it will only work in M.2 slots that support SATA SSDs.

Both modifications of the drive under consideration carry four flash memory chips. On a 120GB drive, it's a Micron MT29F256G08CECABH6, and on a 240GB drive it's MT29F512G08CKCABH7. Both types of chips are assembled from 128-gigabit 20-nm MLC NAND crystals, respectively, in the 120-gigabyte version of the drive, the eight-channel controller has one flash memory device on each of its channels, and in the 240-gigabyte SSD it uses two-fold device interleaving. This explains the noticeable performance differences between the Crucial M500 in different sizes. But both modifications of the Crucial M500 under consideration are equipped with the same amount of RAM. Both SSDs have a 256MB DDR3-1600 chip.

It should be noted that one of the positive features of Crucial consumer drives is hardware data integrity protection during sudden power outages. M.2 modifications of the Crucial M500 also have this property: despite the board size, flash drives are equipped with a capacitor bank, which allows the controller to regularly complete its operation and save the address translation table in non-volatile memory even in case of any excesses.

Crucial M550

Crucial was one of the first to adopt the new form factor, duplicating all of its consumer SSD models in both the traditional 2.5-inch format and M.2 cards. Not surprisingly, after the introduction of the M.2 versions of the M500, the corresponding modifications of the newer and more productive Crucial M550 were released on the market. The general approach to the design of such SSDs has remained: in fact, we got tracing paper from a 2.5-inch SATA model, but squeezed into the frames of an M.2 card. So from an architectural point of view, the M.2 variant of the Crucial M550 is not surprising at all. This is a drive based on the Marvell 88SS9189 controller, which uses Micron's MLC NAND, manufactured according to 20nm standards.

Recall that the Crucial M550 until recently was the flagship drive of this manufacturer, so the engineers not only equipped it with an advanced controller, but also tried to give the flash memory array the maximum level of parallelism. Therefore, in modifications of the Crucial M550 with a volume of up to half a terabyte, MLC NAND with 64-gigabit cores is used.

We got a 128GB sample of the Crucial M550 for testing. This drive is an M.2 card of the 2280 standard format, which is equipped with two keys of type B and M. So, you can install this drive in any slot, but for it to work, this slot needs to support the SATA interface, through which any version of Crucial works M550.

Crucial M550 128GB (CT128M550SSD4)

The motherboard of the 128 GB Crucial M550 drive we received is of interest because all the microcircuits on it are located only on one side. This allows it to be successfully used in ultra-thin portable systems in the so-called one-sided S2 / S3 slots, where the rear surface of the drive's PCB is pressed against the motherboard. For most users, this is not important, but, unfortunately, the struggle to reduce the thickness turned into the fact that the capacitors had to be removed from the drive, which give an additional guarantee of data integrity in case of sudden power outages. There are vacancies for them on the printed circuit board, but they are empty.

The entire Crucial M550's 128GB flash array is housed in two chips. Obviously, in this case, chips are used, which contain eight 64-gigabit semiconductor crystals. This means that the Marvell 88SS9189 controller on the SSD model in question can use 2x interleaving. A 256 MB LPDDR2-1067 microcircuit is used as a RAM.

The M.2 versions of the Crucial M550, like the Crucial M500, along with their more imposing 2.5-inch siblings, support AES-256 hardware encryption without causing performance degradation. Moreover, it fully complies with the Microsoft eDrive specification, which means that you can manage flash memory encryption directly from the Windows environment, for example, using the standard BitLocker tool.

Kingston SM2280S3

Kingston has taken a somewhat non-standard path for its M.2 SSD niche. She did not release M.2 versions of the models she already had, but designed a separate SSD, which has no analogues in other form factors. Moreover, the hardware platform was not the second-generation SandForce controller, which Kingston continues to install in almost all of its 2.5-inch flash drives, but the Phison PS3108-S8 chip, chosen as a budget platform by third-tier SSD manufacturers. And this means that, despite its uniqueness, Kingston SM2280S3 is not something special: it is focused on the lower price segment, and its controller has a SATA interface and naturally does not use all the capabilities of M.2.

For testing, we were provided with a 120 GB version of this drive. It looks like this.

Kingston SM2280S3 120 GB (SM2280S3 / 120G)

As the name suggests, this SSD uses an M.2 card in 2280 format. And since it works over the SATA 6 Gb / s interface, the blade connector of the drive has two cutout keys at once: type B and type M. That is, physically install the Kingston SM2280S3 can be used in any M.2 slot, but for operation it will require the SATA interface to be supported by this slot.

The hardware configuration of the Kingston SM2280S3 is similar to numerous 2.5-inch flash drives with a similar controller. Among them, we, for example, considered Silicon Power Slim S55. Like the Silicon Power product, the Kingston SM2280S3 is equipped with Toshiba flash memory. Although the microcircuits installed on the SSD in question are relabeled, by indirect indications, with a high degree of certainty, it can be argued that they use 64-gigabit MLC NAND crystals, released according to the 19-nm process technology. Thus, the eight-channel Phison PS3108-S8 controller in the Kingston SM2280S3 can use two-fold device interleaving in each of its channels. In addition, the SSD board also has a 256MB DDR3L-1333 SDRAM chip, which works in tandem with the controller and is used by it as RAM.

An interesting feature of the Kingston SM2280S3: the manufacturer claims an unusually large resource for it. The official specs allow 1.8 times the storage capacity to be written to this SSD every day. True, performance in such harsh conditions is only guaranteed for three years, but this still means that a 120 GB M.2 drive from Kingston can store up to 230 TB of data.

Plextor M6e

Plextor M6e is a solid-state drive, which we have already written about more than once, but as a solution installed in PCI Express slots. However, along with such heavyweight versions, the manufacturer also offers M.2 variants of the M6e, since those drives that are proposed to be installed in PCI Express slots are actually assembled on the basis of miniature cards in the M.2 form factor. But the most interesting thing about the Plextor drive is not even this, but the fact that it radically differs from all other participants in the review by using the PCI Express bus, not the SATA interface.

In other words, the Plextor M6e is a flagship device whose performance is not limited by the 600 MB / s SATA bandwidth. It is based on an eight-channel Marvell 88SS9183 controller, which transfers data from an SSD over two PCI Express 2.0 lanes, which in theory allows a maximum throughput of about 800 MB / s. On the flash memory side, the Plextor M6e is similar to many other modern SSDs: it uses Toshiba's MLC NAND, which is manufactured using the first generation 19nm process technology.

Two M.2 versions of the Plextor M6e took part in our testing: 128 GB and 256 GB.

Plextor M6e 128 GB (PX-G128M6e)

Plextor M6e 256GB (PX-G256M6e)

Both M.2 variants of the drive are located on cards with a size of 22 × 80 mm. Moreover, note that their blade connector has cutouts in key positions B and M. And although, according to the specification, the Plextor M6e, which uses the PCIe x2 bus for connection, should have only one type B key, the developers added a second key to it for compatibility. ... As a result, the Plextor M6e can be installed in slots connected to four PCIe lanes, but the drive will naturally not work faster because of this. Therefore, the M6e is primarily suitable for those M.2 slots that are found on many modern motherboards based on Intel's H97 / Z97 chipsets and are powered by a pair of PCIe chipset lanes.

In addition to the Marvell 88SS9183 controller, the M6e boards each have eight Toshiba flash memory chips. In the 128 GB version of the drive, these chips contain two 64-gigabit MLC NAND crystals, while the 256 GB drive contains four such cores in each chip. Thus, in the first case, the controller uses a two-fold alternation of devices in its channels, and in the second, a four-fold alternation. In addition, the boards are equipped with a DDR3-1333 chip that plays the role of RAM. Its capacity is different - 256 MB for the younger version of the SSD and 512 MB for the older one.

Despite the fact that the use of M.2 slots and PCI Express bus for connecting SSDs is a relatively new trend, there are no problems with the Plextor M6e compatibility. Since they work through the standard AHCI protocol, when installed in compatible M.2 slots (that is, those that support PCIe drives) they are found in the motherboard BIOS along with regular drives. Accordingly, there are no problems in their assignment as starting devices, and the operating system does not require special drivers for the M6e to work. In other words, these M.2 PCIe SSDs perform in exactly the same way as their M.2 SATA siblings.

SanDisk X300s

SanDisk is following the same strategy as Crucial for M.2 drives, repeating its 2.5-inch SATA SSDs in this format. However, this does not apply to all consumer products, but only to business models. This also applies to the SanDisk X300s M.2 form factor - we are dealing with a drive based on a Marvell 88SS9188 four-channel controller and SanDisk proprietary MLC flash memory, produced using the second generation 19-nm process technology.

Do not forget that SanDisk X300s, like any other SSD from this manufacturer, has one more feature - nCache technology. Within its framework, a small part of MLC NAND operates in fast SLC mode and is used for caching and consolidating write operations. This allows the X300s to deliver decent performance despite its four-channel controller architecture.

For testing, we were provided with a sample of SanDisk X300s with a volume of 256 GB. He looked like this.

SanDisk X300s 256GB (SD7UN3Q-256G-1122)

It immediately strikes the eye that the drive's board is one-sided, that is, it is compatible with "thin" M.2 slots, which are used in some ultrabooks, allowing you to save an additional one and a half millimeters of thickness. Otherwise, nothing unusual: the board format is the usual 22 × 80 mm; for maximum mechanical compatibility, the blade connector is equipped with both types of key cutouts. The SanDisk X300s requires an M.2 slot with support for the SATA 6 Gb / s interface, that is, in this case, we again have a drive in a new format, but working according to the old rules and not using the opening data transfer capabilities on the PCI Express bus.

On the SanDisk X300s 256 GB board, in addition to the base Marvell 88SS9188 controller and the RAM chip, there are four flash memory chips, each of which contains eight 19-nm 64 Gbit MLC NAND semiconductor crystals. Thus, the controller uses eightfold interleaving of devices, which ultimately gives a fairly high degree of parallelism of the flash memory array.

The SanDisk X300s is unique not only in its hardware architecture, which is based on the Marvell's four-channel controller. Focusing on business use, it can offer enterprise-grade hardware encryption without introducing any latency to SSD performance. The AES-256 hardware engine not only meets TCG Opal 2.0 and IEEE-1667 specifications, but is also certified by leading enterprise data protection software vendors such as Wave, McAfee, WinMagic, Checkpoint, Softex and Absolute Software.

Transcend MTS600 and MTS800

We have combined the story about the two drives from Transcend, because, according to the manufacturer, in terms of architecture, they are almost completely identical. Indeed, a similar element base is used for them and the same performance indicators are declared. The differences, according to the official version, lie only in the different sizes of the M.2 cards on which they are collected. The MTS600 and MTS800 are based on Transcend's proprietary TS6500 chip, which is actually a relabeled Silicon Motion SM2246EN controller. This means that the M.2 SSDs from Transcend that came to us for tests are similar in their filling to the rather popular 2.5-inch SSD370 offered by the same company. Thus, Transcend's M.2 flash drives, like many other models in our testing, use the SATA 6Gb / s interface.

It should be emphasized that the Silicon Motion SM2246EN controller is usually used in budget products, since it has a four-channel architecture. It is with this aim that the Transcend MTS600 and MTS800 were designed. Together with a simple controller, these SSDs also use Micron's inexpensive 20nm flash with 128GB cores, making the MTS600 and MTS800 some of the cheapest M.2 SSDs in our testing today.

We tested the Transcend MTS600 and MTS800 with a capacity of 256 GB. I must say that in appearance they turned out to be completely different from each other.

Transcend MTS600 256 GB (TS256GMTS600)

Transcend MTS800 256 GB (TS256GMTS800)

The matter is in size: the MTS600 model uses the M.2 2260 format, and the MTS800 uses the M.2 2280 format. This means that the length of the cards of these SSDs diverges by as much as 2 cm. But the knife slot for both drives is the same and has two slots in positions B and M. Accordingly, there is no mechanical compatibility limitation, however, these SSDs require M.2 slot support for SATA interface.

The boards of both drives are equipped with a Transcend TS6500 controller and a 256MB DDR3-1600 SDRAM chip used as RAM. But the flash memory chips of the drives are unexpectedly different, which is clearly seen from their markings. The number and organization of these microcircuits is the same: four chips, each of which contains four 128-gigabit MLC NAND devices, manufactured using a 20-nm process technology. The differences are that they use different voltage levels and have slightly different timings. Thus, despite the manufacturer's assurances, the MTS600 and MTS800 still differ somewhat in their characteristics: the first SSD of this pair has memory with a slightly lower latency. However, perhaps this is not due to some subtle marketing calculation, but to the fact that different memory units can be installed on different batches of drives.

An interesting fact: Transcend decided to adopt the tactics of Kingston and began to guarantee a very impressive resource for its SSDs. For example, for the models under consideration with a capacity of 256 GB, it is promised the ability to record up to 380 TB of data. This is significantly more than the declared endurance of the drives of the market leaders.

⇡ Comparative characteristics of tested SSD

	Crucial M500 120GB	Crucial M500 240GB	Crucial M550 128GB	Kingston SM2280S3 120 GB	Plextor M6e 128 GB	Plextor M6e 256 GB	SanDisk X300s 256 GB	Transcend MTS600 256 GB	Transcend MTS800 256 GB
Form factor	M.2 2280	M.2 2280	M.2 2280	M.2 2280	M.2 2280	M.2 2280	M.2 2280	M.2 2260	M.2 2280
Interface	SATA 6Gb / s	SATA 6Gb / s	SATA 6Gb / s	SATA 6Gb / s	PCIe 2.0 x2	PCIe 2.0 x2	SATA 6Gb / s	SATA 6Gb / s	SATA 6Gb / s
Controller	Marvell 88SS9187	Marvell 88SS9187	Marvell 88SS9189	Phison PS3108-S8	Marvell 88SS9183	Marvell 88SS9183	Marvell 88SS9188	Silicon Motion SM2246EN	Silicon Motion SM2246EN
DRAM cache	256 MB	256 MB	256 MB	256 MB	256 MB	512 MB	512 MB	256 MB	256 MB
Flash memory		Micron 128Gbps 20nm MLC NAND	Micron 64Gbps 20nm MLC NAND		Toshiba 64Gb 19nm MLC NAND	Toshiba 64Gb 19nm MLC NAND	SanDisk 64Gbps A19nm MLC NAND	Micron 128Gbps 20nm MLC NAND	Micron 128Gbps 20nm MLC NAND
Sequential read speed	500 MB / s	500 MB / s	550 MB / s	500 MB / s	770 MB / s	770 MB / s	520 MB / s	520 MB / s	520 MB / s
Sequential write speed	130 MB / s	250 MB / s	350 MB / s	330 MB / s	335 MB / s	580 MB / s	460 MB / s	320 MB / s	320 MB / s
Random read speed	62000 IOPS	72000 IOPS	90,000 IOPS	66000 IOPS	96000 IOPS	105000 IOPS	90,000 IOPS	75000 IOPS	75000 IOPS
Random write speed	35000 IOPS	60,000 IOPS	75000 IOPS	65000 IOPS	83000 IOPS	100,000 IOPS	80,000 IOPS	75000 IOPS	75000 IOPS
Recording resource	72 TB	72 TB	72 TB	230 TB	N / a	N / a	80 TB	380 TB	380 TB
Guarantee period	3 years	3 years	3 years	3 years	5 years	5 years	5 years	3 years	3 years

Testing technique

Testing is carried out in the operating system Microsoft Windows 8.1 Professional x64 with Update, which correctly recognizes and maintains modern solid-state drives. This means that the TRIM command is supported and actively used during the tests, as in normal day-to-day use of the SSD. Performance is measured with drives in a "used" state by pre-filling them with data. Drives are cleaned and serviced by the TRIM command before each test. There is a 15-minute pause between individual tests, which is allotted for the correct practice of garbage collection technology. All tests, unless otherwise noted, use random, incompressible data.

Applications and tests used:

Iometer 1.1.0

Measuring the speed of sequential read and write data in blocks of 256 KB (the most typical block size for sequential operations in desktop tasks). The estimation of the speeds is carried out within a minute, after which the average is calculated.
Measuring the speed of random read and write in 4 KB blocks (this block size is used in the overwhelming majority of real operations). The test is carried out twice - without a request queue and with a request queue with a depth of 4 commands (typical for desktop applications that actively work with a branched file system). Data blocks are aligned relative to the flash drive pages. The assessment of the speeds is carried out within three minutes, after which the average is calculated.
Determination of the dependence of the random read and write speeds during operation of a drive with 4K blocks on the depth of the request queue (in the range from one to 32 commands). Data blocks are aligned relative to the flash drive pages. The assessment of the speeds is carried out within three minutes, after which the average is calculated.
Determination of the dependence of the random read and write speeds when the drive is operating with blocks of different sizes. Blocks from 512 bytes to 256 KB in size are used. The depth of the request queue during the test is 4 commands. Data blocks are aligned relative to the flash drive pages. The assessment of the speeds is carried out within three minutes, after which the average is calculated.
Measurement of performance under a mixed multithreaded load and establishing its dependence on the ratio between read and write operations. Sequential operations of reading and writing of 128 KB blocks are used, performed in two independent streams. The ratio between read and write operations varies in 10 percent increments. The assessment of the speeds is carried out within three minutes, after which the average is calculated.
Investigation of SSD performance degradation when processing a continuous random write workflow. The blocks are 4 KB and the queue depth is 32 commands. Data blocks are aligned relative to the flash drive pages. The test duration is two hours, instantaneous speed measurements are carried out every second. At the end of the test, the ability of the drive to restore its performance to its original values is additionally checked due to the work of the garbage collection technology and after the TRIM command has been executed.

CrystalDiskMark 3.0.3b
A synthetic benchmark that provides typical performance metrics for solid-state drives, measured on a 1GB disk area “on top” of the file system. Of the entire set of parameters that can be estimated using this utility, we pay attention to the sequential read and write speed, as well as the random read and write performance in 4K blocks without a request queue and with a queue of 32 commands deep.
PCMark 8 2.0
A benchmark based on the emulation of a real disk load, which is typical for various popular applications. On the tested drive, a single NTFS partition is created for the entire available space, and the Secondary Storage test is carried out in PCMark 8. As test results, both the final performance and the execution speed of individual test traces generated by various applications are taken into account.
File copy tests
This test measures the speed of copying directories with files of different types, as well as the speed of archiving and unzipping files inside the drive. To copy, a standard Windows tool is used - the Robocopy utility, while archiving and unpacking - the 7-zip archiver version 9.22 beta is used. Three sets of files are involved in the tests: ISO - a set that includes several disk images with software distributions; Program - a set, which is a preinstalled software package; Work is a set of work files that includes office documents, photographs and illustrations, pdf files and multimedia content. Each of the sets has a total file size of 8 GB.

⇡ Test stand

The test platform is a computer with an ASUS Z97-Pro motherboard, a Core i5-4690K processor with an integrated Intel HD Graphics 4600 graphics core, and 16 GB DDR3-2133 SDRAM. This motherboard has a standard M.2 slot, in which drives are tested. It should be emphasized that this M.2 slot is supported by the Intel Z97 chipset and supports SATA 6 Gb / s and PCI Express 2.0 x2 modes. Considering that all SSDs participating in this comparison use either the first or the second connection option, the capabilities of this slot in the context of this testing are quite sufficient. The operation of solid state drives in the operating system is provided by the Intel Rapid Storage Technology (RST) 13.2.4.1000 driver.

The volume and speed of data transfer in benchmarks are indicated in binary units (1 KB = 1024 bytes).

⇡ Test participants

The complete list of M.2 drives in this comparison is as follows:

Crucial M500 120GB (CT120M500SSD4, firmware MU05)
Crucial M500 240GB (CT120M500SSD4, firmware MU05)
Crucial M550 128GB (CT128M550SSD4, firmware MU02);
Kingston SM2280S3 120 GB (SM2280S3 / 120G, firmware S8FM06.A);
Plextor M6e 128 GB (PX-G128M6e, firmware 1.05);
Plextor M6e 256 GB (PX-G256M6e, firmware 1.05);
SanDisk X300s 256 GB (SD7UN3Q-256G-1122, firmware X2170300);
Transcend MTS600 256 GB (TS256GMTS600, firmware N0815B);
Transcend MTS800 256 GB (TS256GMTS800, N0815B).

⇡ Performance

Sequential read and write operations

It must be said right away that since M.2 drives do not have any fundamental differences from conventional 2.5-inch or PCI Express models, and use the same interfaces for connection, their performance is generally similar to the performance of SSDs we are used to. In particular, the sequential read speed, as it usually happens, approaches the interface bandwidth, and in this parameter both Plextor M6e modifications, which work via the PCIe x2 bus, are ahead.

The write speed is determined by the peculiarities of the internal structure of specific models, and here the Plextor M6e and SanDisk X300s of 256 GB capacity are in the first place. It just so happens that most of the drives in our test are mid-range and lower-end models, so very few SSDs deliver more than 400 MB / s when writing.

Random read operations

Interestingly, when measuring random read performance, the 256GB PCIe x2 Plextor M6e yields to the SanDisk X300s 256GB flash drive with efficient nCache technology. In other words, it turns out that M.2 SSDs using a SATA connection can compete on an equal footing with PCIe x2 models, at least with those that are on the market at the moment. By the way, of the 128 GB SSDs, the best performance is also not the Plextor product, but the Crucial M550.

A more detailed picture can be seen in the following graph, which shows how SSD performance depends on the depth of the request queue when reading 4K blocks.

As the depth of the request queue grows, Plextor drives still take the lead, but it should be understood that in real tasks this depth rarely exceeds four instructions. The same graph clearly shows the weak points of those SSDs that are built on four-channel controllers. As the workload increases, their results scale much worse, so such products should not be used in applications where complex multi-threaded calls are required.

In addition to this, we propose to see how the random read speed depends on the size of the data block:

Reading in large blocks allows you to again face the limitations of the SATA interface. M.2 form-factor drives using it demonstrate noticeably worse results than their counterparts of the same format, but working via PCIe x2. Moreover, their superiority begins already at 8Kb blocks, which indicates a clear demand for a fast bus.

Random write operations

Random write performance is largely determined by the speed of flash memory used in drives. And it just so happened that the top places in the diagrams were taken by those SSDs that are based on Micron's MLC NAND. But the most surprising thing is that the Crucial M550 128 MB stands out with the best performance, even despite its small size, which does not allow the controller to use the most efficient interleaving of flash memory devices in its channels.

In general, the dependence of the speed of random writing in 4 KB blocks on the depth of the request queue looks like this:

The performance of the Crucial M550 is evident at all but maximum queue depth. But the drives from the same manufacturer, but from the previous M500 line, on the contrary, differ in extremely low speed when writing data.

The following graph shows the dependence of the performance of random records on the size of the data block.

While Plextor drives showed the highest performance when reading in large blocks due to the higher bandwidth of the interface they use, only the 256 GB version of the M6e shines with high performance when writing. A similar SSD with half the size turns out to be no better than other models working via SATA, among which, by the way, the Crucial M550 128 GB stands out again. This solid state drive appears to be the most efficient SSD for write-dominated environments.

As the cost becomes cheaper, solid-state drives are no longer used as exclusively system drives and become ordinary scratch disks. In such situations, the SSD receives not only the refined load in the form of writing or reading, but also mixed requests, when read and write operations are initiated by different applications and must be processed simultaneously. However, full duplex operation for modern SSD controllers remains a significant challenge. Mixing reads and writes in the same queue slows down the speed of most consumer-grade SSDs. This was the reason for a separate study, in which we test how SSDs perform when it is necessary to handle sequential operations that come in interleaving. The following diagram shows the most common case for desktops, when the ratio of the number of reads and writes is 4 to 1.

Both Plextor M6e hold the lead here. They are strong in sequential read operations and mixing some small fraction of writes with them does not harm these drives at all. In second place is the Crucial M550: it held up confidently in clean operations and continues to demonstrate good performance even under mixed load.

The following graph gives a more detailed picture of performance under a mixed load, showing the dependence of the speed of an SSD on the ratio of read and write operations to it.

Given the ratios between read and write operations, where the speed of the SSD is not determined by the interface bandwidth, the results of almost all test participants fall into a tight group, behind which only three outsiders lag behind: Crucial M500 120 GB, SanDisk X300s 256 GB and Kingston SM2280S3 120 GB.

PCMark 8 2.0 Real-World Use Cases

The Futuremark PCMark 8 2.0 test suite is interesting in that it is not of a synthetic nature, but, on the contrary, is based on the work of real applications. In the course of its passage, real scenarios of using the disk in common desktop tasks are reproduced and the speed of their execution is measured. The current version of this test simulates a load taken from real gaming applications Battlefield 3 and World of Warcraft and software packages from Abobe and Microsoft: After Effects, Illustrator, InDesign, Photoshop, Excel, PowerPoint and Word. The final result is calculated in the form of the average speed shown by drives when passing test tracks.

The first two places in PCMark 8 are won by Plextor M6e with 128 and 256 GB volumes. It turns out that in real work in applications, these drives, whose strength is not the SATA interface, but the PCIe x2, still surpass the rest of the M.2 SSD based on the architecture borrowed from the 2.5-inch models. And among the significantly cheaper SATA models, the best performance is given by the Crucial M550 120 GB and SanDisk X300s 256 GB, that is, those SSDs that are based on Marvell controllers.

The integral result of PCMark 8 must be supplemented with the performance indicators given by flash drives when passing separate test tracks, which simulate various variants of real load. The point is that flash drives often behave slightly differently under different loads.

Plextor drives show excellent performance in all applications from the PCMark 8 list. SATA SSDs, unfortunately, can only compete with them in World of Warcraft. However, this is primarily due not to the fact that Plextor M6e are capable of delivering unattainable speed, but with the fact that among the M.2 SATA SSD models we received for testing, there were no proposals, for example, from Samsung or new Crucial drives, which are quite capable of competing in speed with the Plextor M6e PCIe x2 drive.

Copying files

Bearing in mind that solid-state drives are being introduced into personal computers more and more, we decided to add performance measurement to our methodology for ordinary file operations - when copying and working with archivers - that are performed "inside" the drive. This is a typical disk activity that occurs when an SSD is not acting as a system drive, but as a regular disk.

Copying, as another example of a real load, once again brings Plextor drives working through the PCIe x2 bus to the first positions. Of the models with the SATA interface, the Crucial M550 128 GB and the Transcend MTS600 256 GB can boast of the best results. By the way, please note that this model of SSD from Transcend in real work turned out to be noticeably better than Transcend MTS800, so these drives are still not entirely identical in their performance.

The second group of tests was carried out when zipping and unzipping a directory with working files. The fundamental difference between this case is that half of the operations are performed with scattered files, and the other half - with one large archive file.

Here the situation differs from copying only in that SanDisk X300s 256 GB is added to the number of SATA-models of drives that demonstrate relatively good performance.

TRIM and background garbage collection

When testing various solid state drives, we always check how they handle the TRIM command and whether they are able to collect garbage and recover their performance without support from the operating system, that is, in a situation where the TRIM command is not transmitted. Such testing was carried out this time as well. The scheme of this test is standard: after creating a long continuous load on data writing, which leads to degradation of the write speed, we disable TRIM support and wait 15 minutes, during which the SSD can try to recover on its own using its own garbage collection algorithm, but without outside help. operating system, and measure the speed. Then the TRIM command is forcibly sent to the drive - and after a short pause, the speed is measured again.

The results of such testing are shown in the following table, where for each tested model it is indicated whether it responds to TRIM by clearing unused portion of flash memory and whether it can prepare blank pages of flash memory for future operations if the TRIM command is not sent to it. For drives that turned out to be able to carry out garbage collection without the TRIM command, we also indicated the amount of flash memory that was independently released by the SSD controller for future operations. For the case of using the drive in an environment without TRIM support, this is exactly the amount of data that can be saved to the drive at a high initial speed after an idle time.

	TRIM	Without TRIM
	TRIM	Garbage collection	The amount of free flash memory
Crucial M500 120GB	Working	Working	0.9 GB
Crucial M500 240GB	Working	Working	1.7 GB
Crucial M550 128GB	Working	Working	1.8 GB
Kingston SM2280S3 120 GB	Working	Working	7.6 GB
Plextor M6e 128 GB	Working	Working	1.9 GB
Plextor M6e 256 GB	Working	Working	12.7 GB
SanDisk X300s 256 GB	Working	Does not work	-
Transcend MTS600 256 GB	Working	Working	2.7 GB
Transcend MTS800 256 GB	Working	Working	2.7 GB

All M.2 drives that passed our testing process the TRIM command normally. And it would be strange if in 2015 some of the SSDs suddenly failed to cope with this, one might say basic, function. But with a more complex task - garbage collection without support from the operating system - the situation is different. The most efficient algorithms that allow proactively freeing the largest amount of flash memory for future writes are the Kingston SM2280S3 based on the Phison S8 controller and the Plextor M6e 256 GB with the Marvell 88SS9183 controller. Curiously, Plextor's 128GB PCIe version is much less efficient at garbage collection. However, in any case, almost all of the tested drives in the moments of idle time are engaged in reorganizing data in flash memory and preparing it for the rapid execution of subsequent operations. There is only one exception - SanDisk X300s 256 GB, for which garbage collection does not work in principle without TRIM.

It should be remembered, however, that for modern SSDs, the need for a TRIM-free garbage collection can be questioned. All current versions of common operating systems support TRIM, so it would be wrong to assume that the SanDisk X300s, in which offline garbage collection does not work, is fundamentally worse than the other SSDs featured in this review. In everyday use, such a feature is unlikely to manifest itself in any way.

⇡ Conclusions

So, the variety of ways to complete personal computers with solid state drives has increased. To the three already familiar options - connecting to a SATA port, into an mSATA slot or installing into a PCI Express slot - another one was added: SSDs appeared on sale in the form of M.2 form factor boards, and in various platforms you can often find the corresponding connectors ... The question involuntarily arises: are M.2 drives of all other SSD varieties better or worse?

In theory, the M.2 standard does offer more options than other connectivity options. And the point here is not only that M.2 cards are compact, have a size convenient for placing flash memory chips and can be used in platforms that are completely different in their purpose and level of portability. M.2 is also a more flexible and forward-looking standard. It allows the system to interact with SSDs using both the traditional SATA protocol and the PCI Express bus, which opens up space for the industry to create faster flash drives, the maximum speed of which is not limited to 600 MB / s and the exchange of data with which is not necessary is performed using the AHCI protocol with high overhead costs.

Another thing is that in practice all this splendor has not yet been fully revealed. Most of the models of M.2 drives available today are based on exactly the same architecture as their 2.5-inch counterparts, which means that they work through the same SATA interface that has set the teeth on edge. Almost all SSDs in the M.2 form factor we reviewed turned out to be analogs of any models of the usual format, and therefore they offer characteristics that are completely typical for mass solid-state drives, including the level of performance. The only original M.2 drive from the range of products available in domestic stores is only the Plextor M6e, which operates via the PCIe x2 interface, which makes it faster than all its competitors in sequential operations. But even it cannot be called an ideal SSD in M.2 format: the Plextor M6e uses a relatively weak controller, which leads to its low performance under random access loads.

So is it worth striving to fill an M.2 slot with an SSD if your motherboard has one? If you do not take into account those mobile configurations that other SSD options simply do not allow, then, frankly, now there are no obvious arguments in favor of a positive answer to this question. However, we cannot give negative arguments either. In fact, by purchasing and installing an M.2 SSD in your system, you get about the same as if you were using a standard 2.5-inch SATA SSD. At the same time, M.2 cards, on average, are slightly more expensive than full-size drives (and sometimes vice versa), but they allow you to get a more compact platform and free up an extra compartment in the case. What is more important in each specific case is up to you.

But if in the end you decide to purchase an SSD in the M.2 form factor, then we recommend that you pay attention to the following models from the number of commercially available options:

Plextor M6e... The only M.2 drive with PCIe 2.0 x2 interface available in domestic retail. Due to the increased bandwidth of the interface, it demonstrates high speeds during sequential operations, which makes it a high-performance solution even under some types of real load. Unfortunately, the cost of such an SSD is noticeably higher than that of models working via SATA.
Crucial M550... An excellent 2.5-inch drive has an almost identical analogue in M.2-format. Compact versions of the Crucial M550 are as fast and omnivorous as the full-size flash drives of the same name, and the only feature that was lost with the transition to M.2 is hardware data integrity protection from sudden power outages.
SanDisk X300s... This drive in the M.2 form factor is also an analogue of a very good 2.5-inch model. It may not be as powerful as the flagship SSDs, but its undoubted advantages are a five-year warranty and compatibility with a wide range of enterprise-grade encryption tools.
Transcend MTS600... Transcend's budget drive offers perhaps the best price / performance ratio of any model we tested. This is what makes it interesting - it is a very worthy solution for inexpensive platforms.

⇡ Unity and Diversity of the World M.2

SSD interface	Maximum theoretical bandwidth	Maximum real throughput (estimate)
SATA III	6 Gbps (750 MB / s)	600 MB / s
PCIe 2.0 x2	8 Gbps (1 Gbps)	800 MB / s
PCIe 2.0 x4	16 Gbps (2 Gbps)	1.6 GB / s
PCIe 3.0 x4	32 Gbps (4 Gbps)	3.2 GB / s

	Blade connector with key type B	Blade connector with key type M	Blade connector with keys type B and M
Scheme
Location of the slots	Contacts 12-19	Contacts 59-66	Contacts 12-19 and 59-66
SSD interface	PCIe x2	PCIe x4	PCIe x2, PCIe x4, or SATA
Mechanical compatibility	M.2 slot with type B key	M.2 slot with M key	M.2 slots with Type B or Type M keys
Common SSD models	Not	Samsung XP941 (PCIe x4)	Most M.2 SATA SSD Plextor M6e (PCIe x2)

However, if your computer or motherboard has an M.2 slot and you plan to fill it with an SSD, there are a few things you need to check first:

Does your system support M.2 SATA SSD, M.2 PCIe SSD, or both?
If the system supports M.2 PCIe drives, how many PCI Express lanes are there on the M.2 slot?
What arrangement of keys on the SSD card allows for the M.2 slot in the system?
What is the maximum length of an M.2 card that can fit into your motherboard?

And only after you can definitely answer all these questions, you can proceed to choosing a suitable SSD model.

The mSATA standard - also known as mini-SATA - was officially introduced in September 2009. It was intended for laptops and other compact PCs in which there was not enough space for a 2.5-inch drive. Now on sale you can even find motherboards equipped with this port. Outwardly, this interface is similar to the PCI Express Mini-Card slot, but on the electrical level there is a difference that cannot be noticed from the outside. In order to be able to install an mSATA drive in the PCI-E Mini-Card slot, the manufacturer must intervene. Namely, the installation of multiplexer chips. These microcircuits will keep track of which card is connected to the PCI-E Mini-Card slot, and depending on this, connect this connector to a PCI-E controller or to SATA. Such an upgrade is always done at the factory, during the assembly of a particular board, and, as a rule, the purpose of the Mini PCI-E slot is either reflected in the specifications or signed near the port itself.

As for the mSATA drives themselves, now they can be found in almost every Ultrabook, because they are much smaller and thinner than their 2.5-inch counterparts.

Bottom up: regular 3.5-inch hard drive; SSD 2.5 inches; mSATA solid state drive

In addition, it is cheaper to use a ready-made mSATA connector in an ultrabook than to invent your own port, as well as manufacture drives for it. Although some ASUS ultrabooks or Apple laptops use their own proprietary connector and drives of the same type.

MSATA connectors are extremely rare in desktop motherboards. But if such a port is unsoldered, then the drive installed in it can be used either as a system disk or as an SSD cache. Intel Smart Response is a good example of this technology, although you can get by with a regular 2.5-inch drive instead of mSATA.

If we talk about the disadvantages of mSATA drives, then, besides the low prevalence, there are only two of them: the volume and the price. Due to the size of the drive, it is impossible to solder more than four memory chips to it, which means that some of the controller's channels will not be used, and in theory, the read and write speeds of such drives may not be very high. However, the manufacturer can to some extent compensate for the small number of involved channels by installing fast memory or one of the LSI SandForce controllers, which supports on-the-fly compression of the data stream.

⇡ Test participants

In this benchmarking test, we decided to go against the rules a little. This time, along with mSATA drives, we will test ordinary SSDs. This is to see if there is a performance difference between the two formats. And if there is, how big it is.

Here is a list of devices representing the mSATA camp:

mSATA Crucial M4 256GB (CT256M4SSD3)
mSATA Kingston SSDNow mS200 120 GB (SMS200S3 / 120G)
mSATA Plextor M5M 256 GB (PX-256M5M)
mSATA Transcend 128 GB (TS128GMSA740)

As for 2.5-inch drives, we have recently tested a lot of such devices, but for this comparison we decided to take only two of them:

2.5-inch SSD Kingston HyperX 3K 120GB (SH103S3 / 120G)
2.5-inch SSD Plextor M5 Pro 256GB (PX-256M5P)

The first, Kingston HyperX 120GB (SH100S3 / 120G), was chosen because of the LSI SandForce SF-2281 controller - a similar controller, the LSI SandForce SF-2241, is installed in one of the mSATA drives. Another drive, the Plextor M5 Pro 256GB (PX-256M5P), is also selected for its controller. It uses Marvell 88SS9187-BLD2. The exact same chip is found in another mSATA drive, Plextor M5M. The 256GB Crucial M4 (CT256M4SSD3) also uses a Marvell controller, but the previous generation uses a Marvell 88SS9174-BLD2. For SSD Transcend, there was no analogue in the list of devices we tested. Alas, a rare JMicron controller is used there.

Manufacturer	Crucial	Kingston	Plextor	Transcend	Kigston	Plextor
Series	M4	mS200	M5M		HyperX	M5 Pro
Model number	CT256M4SSD3	SMS200S3 / 120G	PX-256M5M	TS128GMSA740	SH100S3 / 120G	PX-256M5P
Form factor	mSATA	mSATA	mSATA	mSATA	2.5 inch	2.5 inch
Interface	SATA 6Gb / s	SATA 6Gb / s	SATA 6Gb / s	SATA 6Gb / s	SATA 6Gb / s	SATA 6Gb / s
Capacity, GB	256	120	256	128	120	256
Configuration
Memory chips: type, interface, process technology, manufacturer	MLC, ONFi, 25nm, Micron		MLC, Toggle-Mode DDR 2.0, 19 nm, Toshiba	MLC, Toggle-Mode DDR, ND, SanDisk	MLC, ONFi 2 (sync.), 25nm, Intel	MLC, Toggle-Mode DDR 2.0, 19 nm, Toshiba
Memory chips: number / number of NAND devices in a chip	4 / ND	4/2	4/4	4 / ND	16/1	8/4
Controller	Marvell 88SS9174-BLD2	LSI SandForce SF-2241	Marvell 88SS9187-BLD2	Jmicron JMF667H	LSI SandForce SF-2281	Marvell 88SS9187-BLD2
Buffer: type, size, MB	DDR3 SDRAM, 128	Not	DDR3L-1333 SDRAM, 256	DDR3-1066 SDRAM, 128	No	DDR3 SDRAM 512
Performance
Max. sustained sequential read speed, MB / s	500	550	540	530	555	540
Max. sustained sequential write speed, MB / s	260	520	430	270	510	460
Max. random read speed (4 KB blocks), op./s	45 000	86 000	79 000	68 000	87 000	100 000
Max. random write speed (4 KB blocks), op./s	50 000	48 000	77 000	69 000	70 000	86 000
physical characteristics
Power consumption: idle / read-write, W	ND	0,4/1,8	0.2 / ND	0,3/2,1	0,46/2,0	ND / 0.25
Impact resistance	ND	ND	1500 g	1500 g	1500 g	1500 g (1 ms)
MTBF (mean time between failures), h	1.2 million	1 million	2.4 million	1 million	1 million	> 2.4 million
AFR (annualized failure rate),%	ND	ND	ND	ND	ND	ND
Overall dimensions: LxHxG, mm	50.88x29.88x3.6	50.88x29.88x3.6	50.8x29.8x3.6	50,8x29,85x4	100x69.85x9.5	100x70x7
Weight, g	ND	6,86	9	8	97	70
Warranty period, years	3	3	3	2	3	5
Average retail price, rub.	7 100	4 200	7 300	4 800	6 500	8 400

⇡ Crucial M4 256GB (CT256M4SSD3)

The first mSATA SSD we are reviewing, the Crucial M4 CT256M4SSD3, uses a Marvell 88SS9174 controller. At the time of this writing, it can be considered morally obsolete, because there are already solid-state drives with a Marvell 88SS9187 controller on the market. However, the use of the old controller is fully justified by the fact that this drive was introduced in mid-2012.

We will be testing a 256GB Crucial M4 drive (CT256M4SSD3) but there are also 128GB, 64GB and 32GB SSDs available for sale. The latter model, in our opinion, is best suited for an SSD cache, and not for installing an OS.

Crucial M4 CT256M4SSD3

The Crucial M4 CT256M4SSD3 is equipped with four Micron ONFi 2.x memory chips. The exact version of the interface is not listed, although this is not surprising: many SSD manufacturers have been doing this recently.... The number of NAND devices in each memory chip is also unknown. The controller is paired with 128 MB DDR3 cache memory.

As for the memory, we can say that it is MLC-memory, made according to the 25 nm process technology. Well, and the speed: the established read speed should be 500 MB / s, and write - only 260 MB / s. As for the speed of random read and write, then, according to the manufacturer, it reaches 45,000 IOPS when reading and 50,000 writes.

If we talk about the number of rewriting cycles, then the manufacturer does not directly declare them, although on the official website you can find information that the drive will withstand a daily recording of 40 GB for 5 years.

If we talk about cost, then the average price for the Crucial M4 CT256M4SSD3 will be about 7,100 rubles at the time of this writing. Although in Moscow online stores you can buy this drive a little cheaper - for 6,600 rubles.

⇡ Kingston SSDNow mS200 120 GB (SMS200S3 / 120G)

If a manufacturer wants to make an SSD based on the SandForce platform, then in the overwhelming majority of cases he will choose the LSI SandForce SF-2281 controller. In the case of the Kingston SSDNow mS200, a different controller was chosen - the LSI SandForce SF-2241. As with all SandForce controllers, the SF-2241 uses compression of all recorded information. If the data lends itself well to compression, then the speed of the drive should be good, otherwise it will drop dramatically.

The 120 GB model we are considering is considered the largest in the lineup. In addition to it, on the market you can find Kingston SSDNow mS200 mSATA drives with a volume of 60 and 30 GB.

Kingston SSDNow mS200 120 GB (SMS200S3 / 120G)

The differences between the LSI SandForce SF-2241 and SF-2281 are that the 41st controller supports MLC and SLC chips with capacities up to 128 and 64 Gb, respectively. As for the LSI SandForce SF-2281, it does not have such strict restrictions - it can work with MLC and SLC microcircuits with capacities up to 512 and 128 Gbps. In general, the SF-2241 and SF-2281 controllers are very similar to each other.

LSI SandForce SF-2241 controller

There are four Flash-memory chips with the Toggle-Mode DDR 2.0 interface soldered on the drive's board, which is very unusual for a SandForce controller - usually ONFi chips are used in tandem with it. The memory manufacturer is Toshiba, all the chips are made using the 19-nm process technology. Judging by the marking of the chip cases, each of them contains two NAND devices and, as a result, all eight controller channels are involved (except that the SSD has lost the advantages of interleaving NAND devices on the channels, which would have been possible if these devices were in twice more). Unfortunately, the manufacturer does not report on the number of rewriting cycles. Kingston says it should have 500 MB / s write speeds and 520 MB / s reads. The speed of random reading and writing of 4KB blocks reaches 86,000 and 48,000 IOPS, respectively.

Memory Kingston SSDNow mS200

The average retail price for a 120GB Kingston SSDNow mS200 drive at the time of this writing is RUB 4,200. But if you look properly in Moscow online stores, you can buy this drive cheaper - about 3,950 rubles.

⇡ Plextor M5M 256GB (PX-256M5M)

The Plextor M5M PX-256M5M drive uses the Marvell 88SS9187 controller, which replaces the outdated Marvell 88SS9174, which we already saw in the Crucial M4 256GB drive (CT256M4SSD3). The new controller features support for SATA 3.1 specifications and also allows the TRIM command to be queued along with read / write commands. In addition, the developers of Marvell 88SS9187 promise to increase performance and reduce power consumption - the latter should please the owners of ultrabooks and other mobile PCs. Also, the memory card contains DDR3L-1333 SDRAM cache memory with a volume of 256 MB.

The Plextor M5M 256GB (PX-256M5M) is considered the largest in the range. In addition to the 256 GB model, you can find mSATA SSDs of 128 and 64 GB on sale.

Plextor M5M 256GB (PX-256M5M)

The memory used in the Plextor M5M PX-256M5M is of the Toggle Mode DDR 2.0 type. It is manufactured by Toshiba using a 19 nm process technology. Each chip contains four NAND devices, therefore, all eight controller channels, and even with alternation. As always, the memory manufacturer is silent about the number of rewriting cycles. As for the speed characteristics, the established read speed should be 540 MB / s, and write - 430 MB / s. The random read and write speeds of this drive are similar. So, the declared speed of reading blocks of 4 KB is 79,000 IOPS, and writing - 77,000 IOPS.

At the time of this writing, the average price of a drive is 7,300 rubles, although it is possible to find this drive in Moscow online stores for about 400 rubles cheaper.

⇡ Transcend 128 GB (TS128GMSA740)

The last drive considered in this test - Transcend SSD TS128GMSA740 - is equipped with a Jmicron JMF667H controller, which has four channels for Flash memory, and up to eight NAND devices can be "hung" on each channel. Not forgotten is the wear leveling function and support for Toggle Mode DDR 2.0 memory made using the 19 nm process technology. Also, this controller can blink with LED indicators, if they are soldered on the board.

128GB is the maximum capacity for this line of Transcend mSATA drives. Also on sale you can find SSD from the same series with a volume of 64 and 32 GB.

Transcend SSD 128 GB (TS128GMSA740)

About the memory chips soldered on this SSD, at the time of this writing, it was not possible to find exact information. It is only known that the memory interface is Toggle Mode DDR, although it is not clear what version it is and by what technical process the memory was produced. As for the speed characteristics, the established read speed should be 530 MB / s, and the write speed should be 270 MB / s, which is not very much. The random read speed is 68,000 IOPS, and the write speed is 69,000 IOPS.

At the time of this writing, the average price for a 128 GB Transcend drive (TS128GMSA740) is about 4,800 rubles, but if you try, you can find this drive in Moscow online stores at a lower price: about 3,600 rubles.

That is where we finish the description of mSATA drives and pass on to the story about other test participants. All the drives described below have already participated in our group testing of 14 SSDs with a volume of 240-256 GB, so we will simply provide excerpts from this article.

⇡ Kingston HyperX 3K 120GB (SH100S3 / 120G)

Simple calculations show that an SSD in a client computer will become obsolete long before its memory cells wear out. This means that you can save part of the cost of the drive by using chips with a smaller resource of rewriting cycles. The number in the name Kingston HyperX 3K means exactly that - 3 thousand rewriting cycles, in contrast to the “simple” HyperX, which has a resource of 5 thousand cycles. The interface and technical process for the production of microcircuits remained the same. There is also almost no difference in performance between them, but 3K is still cheaper.

⇡ Plextor M5 Pro 256GB (PX-256M3P)

The M5 Pro is the first SSD to replace the well-deserved Marvell 88SS9174 with the Marvell 88SS9187 controller to increase performance and reduce power consumption.

The Plextor M5 Pro is equipped with Toshiba's Toggle-Mode DDR 2.0 memory, manufactured using the 19 nm process technology. The M5 Pro also features up to 768MB of DDR3 chips in the 512GB model. With such a buffer size, it is obvious that, in addition to service information, the controller also stores user data there.

The Plextor M5 Pro supports AES-128 and AES-256 full disk encryption. To control data integrity, along with the 128-bit ECC mechanism, a certain algorithm is used in the firmware called Robust Data Hold-out. According to the manufacturer, each device undergoes rigorous hardware testing before delivery.

The performance data shown in the table is valid for devices with firmware version 1.02, which the manufacturer also calls Xtreme. With earlier firmware versions, the speed is not much, but still lower. Therefore, all M5 Pro buyers, as well as OCZ Vertex 4 owners, are advised to check the firmware version and update.

Despite the fact that solid-state drives, that is, SSDs, have appeared for a long time, many users are just beginning to learn about them and use them on their computers. Perhaps this is due to the high price and small capacity, although they are faster than standard drives and are significantly faster.

Before delving into the types of hard drives, their manufacturing technologies, types of memory and controllers, it is necessary to focus on the form factor (size). Each of the devices is different in size, has its own connection connectors and is used in completely different ways. If a 2.5-inch SSD does not raise any questions, since it is similar in size and location of connectors to conventional hard drives, then other varieties raise a lot of questions.

Today we will talk about devices such as M.2 SSD drives, what they are, what are their features and advantages. This is a relatively new standard, which, according to many experts, is a revolutionary solution. Let's take a closer look at this topic and find out as much information as possible.

Development of the SATA interface

The SATA interface has become a good replacement for PATA, replacing the wide ribbon cable with a more compact, thin and convenient option. The main tendency of its development was the desire for compactness, and this is quite normal. Even the new interface required a variation that allows it to be used on mobile devices and where there are special requirements for the size of the components.

Thus, mSATA was created - the same interface, only with more compact dimensions. But it did not live long and was quickly replaced by a completely new one - the M.2 connector, which had even greater capabilities. Not by mistake, the abbreviation does not contain the word SATA, since the new version does not apply to this standard. We will talk about this in more detail later.

The only thing that needs to be said is that the M.2 SSD is connected without power cables and cables, thanks to which its use becomes as comfortable as possible and allows the computer to be even more compact. This is one of its key benefits.

M.2 interface overview

M.2 is a connector on an expansion card installed in a PCI-Express slot, or on the motherboard itself. You can install in it not only SSD format M.2, but other modules, including Bluetooth and Wi-Fi. The scope of this connector is wide enough, which makes it incredibly convenient and useful.

When upgrading your computer, be sure to pay attention to it and install a motherboard with this connector, even if you do not plan to install a solid-state drive with such an interface yet.

However, if you have a rather old motherboard, and you do not want to change it, for example "GA-P75-D3" with missing M2 slot, but at the same time it has PCI-E 3.0 with a video card installed and a PCIe x4 slot. In this case, the SSD can be installed on PCIe x4 through a special adapter, but its speed will be slightly lower.

Absolutely all M.2 SSD drives have a flush mount in the M.2 slots. This form factor provides maximum performance with minimum resource consumption and is designed for the technological advancement of hard drives in the future.

Moreover, as mentioned above, cables and loops are not needed for connection, which usually only take up extra space. In order to start working with the device, you just need to insert it into the connector.

M-key and B-key

Today's hard drives, including solid state drives, are connected to the SATA bus. The maximum bandwidth of which is 6 Gb / s, that is, approximately 550-600 Mb / s. Such a speed is simply unattainable for a conventional drive, but SSD drives can reach much higher speeds without any problems. Only their installation is absolutely pointless if the interface cannot "pump" data at a higher speed than the one for which it is designed.

In view of this, it became possible to use the PCI-Express bus with a higher bandwidth:

PCI-Express 2.0. It has two lanes (PCI-E 2.0 x2), is characterized by a bandwidth of up to 8Gb / s, or about 800Mb / s.
PCI-Express 3.0. It has four lanes (PCI-E 3.0 x4), with a bandwidth of 32Gb / s, or approximately 3.2Gb / s.

Which interface is used to connect a particular device determines the position of the jumper.

Currently, SSD M.2 drives have the following key options:

B key "Socket2" (includes support for PCI-E × 2, SATA, Audio, USB and other modules).
M key "Socket3" (includes PCI-E × 4 and SATA support).

For example, let's take a motherboard with an M.2 connector with an M-key. That is, a PCIe × 4 bus is used. Can I install a SATA SSD in it? This is an interesting question that we will try to find an answer to.

You need to open the motherboard information and find out if it supports M.2 SATA or not. Let's say the manufacturer says yes. In this case, a storage disk is bought, which was originally created for PCIe × 4, and absolutely no problems should arise when connecting.

When choosing a motherboard, be sure to pay attention to whether the SATA bus is supported in M.2 so that you can use any hard drive.

Let's recap and summarize all of the above:

M.2 is just a different form factor (connector and size) for solid state drives. All motherboards equipped with this slot use the PCI-E x4 bus.
The type of bus used by the drive depends on the keys. Usually a PCI-Express bus (M key) or SATA (M + B key) is used. The ability to connect a SSD with a SATA interface must be indicated in the characteristics of the motherboard.

Size specification: 2260, 2280 and others

Often looking through the specification of the motherboard of a computer or laptop, you can find the following line "1 x M.2 Socket 3, with M Key, type 2260/2280" - it means that 1 slot M.2 with a key of type M and size 2260/2280 is used. The first two digits "22" are the width in "mm", the second two digits "60" are the length. Therefore, if you choose, say, Transcend TS128GMTS600, with a length of "60mm" and a width of "22mm", then there will be no problems with its installation.

But even if you take the Kingston SHPM2280P2 / 480G with the "2280" type and since the motherboard specifications support this type of drives, it will not be difficult to install it.

The motherboard can support many sizes of installed modules, and in this case, it contains fixing screws that are designed for each length of the strip.

NVMe technology

The old generation of conventional magnetic and SSD disks use the AHCI protocol, which was created relatively long ago and is still supported by many operating systems. But with the advent of more modern and faster SSDs, it cannot cope with its task and cannot use all their capabilities to the maximum.

As a solution to this problem, the NVMe protocol was created. It is characterized by the fastest speed, lower latency and uses the least processor resources when performing operations.

In order for the media to work with this technology, it must support it, so when choosing, pay attention to this separately, just like the motherboard (it must be UEFI-compatible).

Let's summarize

After reviewing the M.2 SSD, we can say that it is the most compact form factor of solid state devices. And if it is supported by the motherboard, it is recommended to use it.

Let's take a look at a few to help you make the right choice. So, first of all, when buying, you should pay attention to the following points:

Does the motherboard have the required M.2 slot and what size of modules it can use (2260, 2280, etc.).
The type of key the slot uses (M, B, or B + M).
Whether the motherboard supports SATA or PCI-E and which version is used (for example, PCIe 3.0 4x).
Whether the operating system, the SSD itself, and the motherboard support AHCI or NVMe.

After all, answering the question which is better, an SSD with a standard slot or M.2, it is clear that you should choose the second option with NVMe support and install it on PCIe 3.0 × 4.

This will not only free up more space by reducing the number of wires, but will also increase transmission speed, system responsiveness and performance. The main thing is that it will make working at the computer more comfortable, enjoyable and efficient.

Detailed video review

Read about the pros and cons of the M.2 form factor, which drives support the M.2 slot, which connectors do M.2 drives use, what is needed to install an M.2 card, etc. M.2 is a new open format for high-performance computing systems, but is it all that simple? Solid state SSD manufacturers such as Samsung, Intel, Plextor, Corsair use this format to save space and energy. These are very important factors in the production of modern ultrabooks and tablets. However, purchasing an M.2 drive to upgrade your device requires some foresight.

M.2 is not just an evolutionary form factor. Potentially, it should completely replace the entire Serial ATA format. M.2 can interoperate with SATA 3.0 (such cables connect all drives on modern desktop PCs), PCI Express 3.0 (this interface is used by default for video cards and other devices) and even USB 3.0.

Potentially any SSD or HDD disk, memory card or flash drive, GPU or any USB gadget with low power consumption can be installed on a card with an M.2 slot. But not everything is so simple. For example, there are only four PCI Express lanes in a single M.2 slot, which is a quarter of the number required by graphics cards, but the flexibility in this tiny little slot is impressive.

By using the PCI bus instead of the SATA bus, M.2 devices can transfer data up to 6 times faster. The final speed depends on the capabilities of the motherboard and the M.2 card itself. An M.2 SSD drive will perform much faster than a comparable SATA drive if your motherboard supports PCI 3.

What drives support the M.2 slot?

Currently, M.2 is used as an interface for ultra-fast SSD drives on both laptops and workstations. If you go to a computer store and ask for an M.2 drive, they will almost certainly show you an M.2 SSD. But only if you can find a computer retail store that is still open today.

Some laptop models also use the M.2 port as their wireless connection, inserting tiny, low-power cards that combine Wi-Fi and Bluetooth radios. This is less common on desktops where USB or PCIe 1x connectors are more convenient (although there is no reason you couldn't do this on a compatible motherboard).

Computer hardware manufacturers are in no hurry to use this slot for other devices. No one has revealed an M.2 video card yet, but Intel is already selling its ultra-fast Optane memory to customers.

Does my computer support M.2 slot?

If your computer has been manufactured and assembled in the past few years, then it almost certainly has an M.2 slot. Unfortunately, the flexibility of the format does not mean that the slot itself is as easy to use as any USB device. As a rule, cards with an M.2 slot are quite long. Before purchasing an M.2 SSD drive, please check the board dimensions according to the specifications and make sure your computer or laptop has room to install them. In addition, M.2 devices have different connectors. Let's take a closer look at these 2 factors.

How long is the M.2 board?

For desktop PCs, length is usually not an issue. Even a tiny Mini-ITX motherboard can easily accommodate an M.2 board that ranges from 30mm to 110mm in length. Typically, motherboards have a small screw hole that holds the board securely in place. The length of the supported M.2 chip is indicated next to the mount.

All M.2 discs use a fixed width of 22 millimeters, so the size difference is only expressed in length. At the moment, the following options are available:

M.2 2230: 30mm;
M.2 2242: 42mm;
M.2 2260: 60mm;
M.2 2280: 80mm;
M.2 2210: 110mm.

Some motherboards offer the ability to mount a screw at any of these intervals.

What connectors do M.2 drives use?

Although the M.2 standard uses the same 22mm wide slot for all cards, it is not the same for all devices. Because M.2 is designed for use with many different devices, it has some connectivity differences:

B Key: uses the gap on the right side of the card (to the left of the host controller), with six pins to the right of the gap. This configuration supports PCIe x2 buses.
M Key: uses a gap on the left side of the card (right side of the main controller), with five pins to the left of the gap. This configuration supports PCIe x4 bus connections for double the data throughput.
B + M Key: uses both of the aforementioned gaps, with five pins on the left side of the card and six on the right. These cards are limited to PCIe x2 speed.

What is required to install an M.2 card?

Most M.2 cards are SSD drives and are automatically recognized by your operating system based on AHCI drivers. For Windows 10, most Wi-Fi and Bluetooth cards are also recognized automatically and standard drivers are installed for them. However, you may need to enable the M.2 slot through a setting in your computer's BIOS or UEFI. You will also need a screwdriver to secure the device with a screw to the motherboard.

Can I add an M.2 card to my PC if it doesn't have a slot?

This is not possible for laptops, as modern devices are very compact in design and do not allow any unplanned device inside the case. You're in luck if you're using a desktop PC. There are adapters on the market that use the PCIe x4 slot of your motherboard.

Remember, if your motherboard cannot boot from PCIe, then you cannot use the M.2 drive as a boot drive, which means you will not benefit from the high speed. If you want to take full advantage of the M.2 drive, it's best to use a motherboard that supports the new standard.

M sata connector. SSD M.2 - Realities of the standard and an overview of the available model Sandisk X300

⇡ Unity and Diversity of the World M.2

⇡ Comparative characteristics of tested SSD

Testing technique

⇡ Test stand

⇡ Test participants

⇡ Performance

⇡ Conclusions

⇡ Unity and Diversity of the World M.2

⇡ Test participants

⇡ Crucial M4 256GB (CT256M4SSD3)

⇡ Kingston SSDNow mS200 120 GB (SMS200S3 / 120G)

⇡ Plextor M5M 256GB (PX-256M5M)

⇡ Transcend 128 GB (TS128GMSA740)

⇡ Kingston HyperX 3K 120GB (SH100S3 / 120G)

⇡ Plextor M5 Pro 256GB (PX-256M3P)

Development of the SATA interface

M.2 interface overview

M-key and B-key

Size specification: 2260, 2280 and others

NVMe technology

Let's summarize

Detailed video review

What drives support the M.2 slot?

Does my computer support M.2 slot?

How long is the M.2 board?

What connectors do M.2 drives use?

What is required to install an M.2 card?

Can I add an M.2 card to my PC if it doesn't have a slot?

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