Today we’ll talk a little about the present non-standard SSDs. The benefits of using solid-state drives have long ceased to be debated - today SSDs are recommended not only for gamers or designers, but also for all ordinary users. While the market is waiting for the release of revolutionary controllers that will take full advantage of PCIe, simplified analogues of the M.2 format confidently hold the lead in this direction. Initially, the “intermediate” form factor (on the way from SATA to full-fledged PCIe) managed to occupy its niche due to several advantages over older standards.

What exactly are the benefits?

First, obviously, speed: M.2 provides operation via the SATA 3.2 interface (6 Gbit/s), and many models support several PCIe lines simultaneously. It is worth mentioning that the controllers do not yet allow full use of the latest interface, but the recording speed was increased from approximately 500 to almost 800 MB/s).

Secondly, compactness. If we compare the sizes of M.2 drives with the previous standard, mSATA, the former can be at least a quarter more compact in size. Initially developed for ultrabooks and portable devices, the standard is now actively supported by manufacturers of motherboards for regular desktop PCs. In this case, for example, the memory capacity of the line SanDisk X300(represented by our SanDisk X300 SD7SN6S model) increases up to 1TB.

Size comparison of review model with OCZ Trion 100 drive

The third advantage is versatility. As mentioned above, some models have the ability to connect to both PCIe and SATA. Today, the difference in speed is not as noticeable as we would like, but the future is obvious for PCIe. But in addition to M.2 drives it supports bluetooth connection, Wi-Fi and NFC chips.

M.2 slot in Asus Maximus VIII Ranger motherboard

And finally, prevalence: so far SATA Express has not received widespread development, the M.2 slot managed to find its place in motherboards from leading manufacturers. As you can see, the standard has become a logical evolutionary branch in the development of the use of SSDs, surpassing mSATA and at the same time being the most compact and fastest solution on the market.

Excursion into history

The history of the development of M.2, like any other standard, contains a number of errors and “childhood diseases”: problems that were solved based on the experience of early shortcomings. The first solid state drive in M.2 can be considered Plextor M6e, not a particularly successful product, which nevertheless gave impetus to development.

It was preceded by other drives (from companies such as Intel, Crucial, KingSpec), but they were designed only for mobile and portable devices. Despite the capabilities of two PCIe 2.0 lanes used in the Plextor M6e, the drive in the new form factor did not give the expected results in terms of performance, and compatibility was hampered by the lack of custom M.2 drives on the market at that time. In fact, it was Plextor that opened up this new direction.

An important problem for a long time remained the reluctance of manufacturers to spend money on full PCIe support: when assembling drives in the M.2 form factor, they still reduced performance to a minimum. There were only a few models available in stores that supported SATA via a 2x or 4x PCIe interface. In this case, the advantage of M.2 over mSATA was only compactness and only slightly increased performance.

In addition, even when using PCIe capabilities, manufacturers resorted to AHCI drivers, although for SSDs it is much more profitable to use NVM Express.

Gradually, the market began to be filled with models from the manufacturers mentioned above: Crucial M500, Transcend MTS600, Kingston SM2280. However, the form factor of these models can still be called “half M.2”: no one wanted to fully use the capabilities of the new standard.

By the way, now the presence of certain keys in the selected drive model can cause difficulties when purchasing: it all depends on the user’s motherboard. Some boards only support drives with B-keys (2xPCIe), some - with M-keys (4xPCIe). It is clear that M is fully compatible with B, but if the “mother” is designed only for models with B-keys, you will have to forget about M-products. The length of the M.2 card will also have to be taken into account: on some boards, long drives with adapters simply will not fit.

Samsung is going to complete the development of M.2: the revolutionary Samsung PRO 950 finally finally switches to 4 PCIe 3.0 interfaces, allowing you to increase the write speed to 1500 MB/s. Samsung has specially developed a new controller that allows you to squeeze the maximum available out of the bus. At 256 GB, the drive's lifespan is equivalent to overwriting 200 TB: about 180 GB of overwriting daily for three years. The drive will go on sale in the near future, and its terabyte version will be available next year.

X300 – not the fastest, but inexpensive horses

But from expensive new products, let's return to firmly established models and talk about an affordable and successful option - Sandisk X300 128GB

Technology, connection

SanDisk is a well-known player in the storage drive market. Their proprietary nCache 2.0 technology (allows you to save device resources when working with small-block data; programmed at the controller level) has earned positive reviews from critics and specialists and is used in many of the manufacturer’s drives. Including in the X300 under consideration.
The drive is connected via the SATA 3.2 interface.

This is what a disk board looks like without a container

An important detail, by the way, is this treasured screw, which, of course, is not included with the disk. You need to look for it in a box with motherboard. There should also be a special pad that is screwed into the board (or it may already be screwed in - depends on the manufacturer).

There are two versions of the drive - 128GB and 512GB with the same screw

The motherboard can accommodate M.2 cards of different lengths. It’s great that we came across exactly this one in the test – ASUS MAXIMUS VIII. It has several fasteners for fixing boards of different lengths.

Sandisk X300 on ASUS MAXIMUS VIII RANGER motherboard

The installed board takes up almost no space in the case. This is, of course, the main advantage in terms of ergonomics - no cables or rigid power cables from the power supply in the grid, with which we have no friendship.

Test results

We ran several tests using various software: the drive was tested on a system with Windows 10 Pro, an i7 processor and 16 GB of RAM.

Test bench:

• OS: Windows 10 Pro
• CPU: i7-6700 @ 3.4GHz
• RAM: 16GB DDR4 @ 2140MHz
• MTHRBRD: ASUS MAXIMUS VIII RANGER

Let us remind you that the read/write speed declared by the manufacturer is 530/470 MB per second.

Test results in Crystal DiskMark:

Results of disk check using HD Tune Pro utility:

Readings from HD Tune Pro utility and standard hard drive diagnostic tool Windows drives while copying a large file from an OCZ Trion 100 drive to a Sandisk X300 drive:

Results of checking the disk using the AS SSD Benchmark utility:

#M.2_key #M.2_socket_3 #M.2_type #M.2_socket #M.2_wifi #2230 #2242 #2260 #2280 #22110

M.2 (NGFF)– the general name of the form factor or physical interface for SSD drives, mobile WiFi adapters, 3G/4G modems and other computer components for miniature devices such as tablets, ultrabooks or nettops.

We have already talked about the new form factor using an example - this material can be found at the link.

However, M.2 was designed not only for SSDs, but also for WiFi, WiGig, Bluetooth adapters, GPS/GLONASS modules (GNSS), NFC modules, and other devices and sensors.

Previously, in mobile devices, the listed modules and adapters were connected using a mini PCI Express connector and had the popular full- or half-length Mini Card form factor. In turn, compact SSD drives had the same Mini Card form factor, but for the mSATA interface.

M.2 or Next Generation Form Factor replaced mSATA and mini PCIe, united and expanded connectivity options, since it is able to work with big amount logical interfaces (Host Interface). In addition, the M.2 connector takes up less space in a mobile device, and there are several times more design options compared to the Mini Card due to the appearance of several M.2 (NGFF) sizes, depending on the width and height.

What you need to know about M.2?

• The M.2 (NGFF) specification includes devices that can be soldered to the motherboard, as well as devices that can be connected to various devices. The M.2 connector takes up 20% less space than the mini PCIe connector. The M.2 connector has a total of 67 pins, which can be separated by partitions - keys. Depending on the type of key, it is assumed that the connected devices are separated according to their intended purpose.


• The logical interfaces for the M.2 connector can be PCI Express, SATA, USB, Display Port, I2C, SDIO, UART and others.


• M.2 device sizes are standardized and grouped into types. The width of M.2 devices can be 12, 16, 22 or 30 millimeters. Length – 16, 26, 30, 38, 42, 60, 80 or 110 millimeters. For example, an M.2 SSD with a width of 22 mm and a length of 80 mm is designated "Type2280". (clearly shown in the schematic diagram of M.2 devices by size).


• The thickness of M.2 devices, more specifically the protruding components at the top and bottom, is also standardized. Devices can be either single-sided or double-sided - elements can be located on one side of the printed circuit board or on two.

Nomenclature designation for M.2 (NGFF) devices

Type XX XX- XX-X-X* Type XX XX-XX- X-X* Future Memory Interface (FMI)

M.2 key name (Key ID)	Number of involved contacts of the M.2 connector, pcs.	M.2 socket logical interface options
A	8-15	PCIe x2 / USB / I2C / DP x4
B	12-19	PCIe x2 / SATA / USB / PMC / IUM / SSIC / UART-I2C
C	16-23
D	20-27	Key reserved for future use
E	24-31	PCIe x2 / USB / I2C-ME / SDIO / UART / PCM
F	28-35
G	39-46	Will not be used for standard M.2 devices. Reserved for third party devices.
H	43-50	Key reserved for future use
J	47-54	Key reserved for future use
K	51-58	Key reserved for future use
L	55-62	Key reserved for future use
M	59-66	PCIe x4/SATA

* - If the second letter of the key is indicated, then the module is universal, compatible with two types of keys in the M.2 connector.

For example, it can be deciphered as follows: width – 22 mm, length 80 mm, double-sided layout, elements protrude 1.35 mm from the top and bottom, suitable for installation in a slot with B or M keys.

In general, manufacturers do not often indicate the nomenclature designation of M.2 modules. But, in fact, the designation can be compiled independently based on visual signs, as well as by simple measurements of the device.

Which M.2 (NGFF) devices use the M.2 connector with keys A, E, B, M?

What are Socket 1, Socket 2, Socket 3 as applied to M.2 (NGFF) devices?

Indeed, the concept of a socket for M.2 devices is encountered. The division principle is clearly shown in the following table:

	Soldered to the motherboard			For installation in M.2 connector
	M.2 module size	Height	Contacts are identical to the key	M.2 connector key	M.2 module size	Module height	M.2 connector key on the module
Socket 1 Typically, communication modules (WIFi adapters, Bluetooth, NFC, etc.)	1216	S1	E
				A, E	1630	S1, D1, S3, D3, D4	A, E, A+E
	2226	S3	E	A, E	2230	S1, D1, S3, D3, D4	A, E, A+E
	3026	S3	A	A, E	3030	S1, D1, S3, D3, D4	A, E, A+E
Socket 2 For compact 3G/4G M.2 modems, but other equipment may appear				B	3042	S1, D1, S3, D3, D4	B
Socket 2 For M.2 SSD and other equipment with a B+M universal key				B	2230	S2, D2, S3, D3, D5	B+M
				B	2242	S2, D2, S3, D3, D5	B+M
				B	2260	S2, D2, S3, D3, D5	B+M
				B	2280	S2, D2, S3, D3, D5	B+M
				B	22110	S2, D2, S3, D3, D5	B+M
Socket 3 Only for SSD drives with M.2 interface (at least for now)				M	2242	S2, D2, S3, D3, D5	M, B+M
				M	2260	S2, D2, S3, D3, D5	M, B+M
				M	2280	S2... D2, S3, D3, D5	M, B+M
				M	22110	S2... D2, S3, D3, D5	M, B+M

From the data in the table it can be seen that Any SSD with a B+M universal key can be installed in the M.2 M Key slot. In its turn It is physically impossible to install an SSD with an M key in slot B, even if the logical interface of the devices is the same.

It is for this reason that motherboard manufacturers SSD installation They make an M.2 connector with an M key and two logical interfaces to choose from - PCIe or SATA. But there are exceptions when the M.2 connector on the board is connected only to the PCIe bus or only to a SATA controller - you need to be more careful with this when choosing the right one.

Whether in the past or this year, articles about SSDs can safely begin with the same passage: “The solid-state drive market is on the verge of serious changes.” For several months now, we have been looking forward to the moment when manufacturers finally begin releasing fundamentally new models of mass-produced SSDs 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 more high-performance solutions, everything is postponed and postponed, mainly due to delays in bringing the necessary controllers to fruition. Those single models of consumer SSDs with the PCI Express bus, which do become available, are still clearly experimental in nature and cannot amaze us with their performance.

Being in such anxious anticipation of change, it is easy to lose sight of other events that, although they do not have a fundamental impact on the entire industry, are nevertheless also important and interesting. Something similar happened to us: new trends, to which we had paid almost no attention until now, have spread unnoticed in the consumer SSD market. SSDs of a new format - M.2 - have begun to appear on sale en masse. Just a couple of years ago, this form factor was talked about 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, today M.2 drives are not a rarity, but an everyday reality. They are produced by many manufacturers, they are freely sold in stores and are installed in computers everywhere. Moreover, the M.2 format has managed to carve out a place for itself not only in mobile systems for which it was originally intended. Many motherboards for desktop computers today are also equipped with an M.2 slot, as a result of which such SSDs are actively penetrating classic desktops as well.

Considering all this, we came to the conclusion that it is necessary to pay close attention to solid-state drives in the M.2 format. Despite the fact that many models of such flash drives are analogues 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 catch up and conduct a single consolidated test of the most popular M.2 SSD capacities available in domestic stores: 128 and 256 GB. 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

Slots and cards of the M.2 format (previously this format was called Next Generation Form Factor - NGFF) were initially 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, M.2 offers fundamentally greater flexibility in both logical and mechanical parts. The new standard describes several options for the length and width of cards, and also allows the use of both SATA and the faster PCI Express interface to connect solid-state drives.

There is no doubt that PCI Express will replace the drive interfaces we are used to. Direct use of this bus without additional add-ons allows you to reduce latencies when accessing data, and thanks to its scalability, it significantly increases throughput. Even two PCI Express 2.0 lines can provide significantly higher data transfer speeds 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 lines. This foundation for throughput growth 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 reduced latency when moving large amounts of data.

SSD interface	Maximum theoretical throughput	Maximum Real Throughput (Estimated)
SATA III	6 Gbit/s (750 MB/s)	600 MB/s
PCIe 2.0 x2	8 Gbit/s (1 GB/s)	800 MB/s
PCIe 2.0 x4	16 Gbit/s (2 GB/s)	1.6 GB/s
PCIe 3.0 x4	32 Gbit/s (4 GB/s)	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, over the past couple of years, M.2 has become much more widespread 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 for sale. SATA Express 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 using the SATA, PCI Express and even USB 3.0 protocols. Moreover, in its maximum version, M.2 supports up to four PCI Express lines, while SATA Express connectors are capable of transmitting data over only two such lines. In other words, today M.2 slots 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, but they are also capable of delivering the highest throughput of any consumer SSD connectivity option available.

However, given the fact that the key property 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 various options for the corresponding slots is a different story. To begin with, the M.2 form factor SSD boards available on the market are 22mm wide, but come in five lengths: 30, 42, 60, 80, or 110mm. This dimension is reflected in the markings, for example, the M.2 2280 form factor means that the drive card is 22 mm wide and 80 mm long. For M.2 slots, a complete list of dimensions of storage cards with which they can be physically compatible is usually indicated.

The second feature that introduces differentiation into different variants M.2 are “keys” in the slot slot and, accordingly, in the blade connector of the cards, which prevent the installation of storage cards in connectors that are logically incompatible with them. At the moment, the M.2 SSD uses two key locations out of eleven different positions described in the specification. Two more options are used on WLAN and Bluetooth cards in the M.2 form factor (yes, this also happens - for example, the Intel 7260NGW wireless adapter), and seven key positions are reserved for the future.

	M.2 slot with 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 only have one key cutout, but M.2 cards can have multiple key cutouts at once, making them compatible with multiple types of slots at the same time. The type B key, located instead of pins numbered 12-19, means that no more than two PCI Express lanes are connected to the slot. The M type key, occupying pin positions 59-66, means that the slot has four PCI Express lanes and therefore can provide higher performance. In other words, the M.2 card must not only be the right size, but also have a key layout compatible with the slot. At the same time, the keys not only limit mechanical compatibility between various connectors and boards of the M.2 form factor, but also perform another function: their location prevents drives from being installed incorrectly in the slot.

The information given in the table should help to correctly identify the type of slot available in the system. But you need to keep in mind that the possibility of mechanical joining of a slot and connector is only a necessary, but not a sufficient condition for their complete logical compatibility. The fact is that slots with keys B and M can accommodate not only the PCI Express interface, but also SATA, but the location of the keys does not provide any information about its absence or presence. The same applies to M.2 card connectors.

	Blade connector with key type B	Blade connector with M type key	Blade connector with B and M keys
Scheme
Slot location	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 B key	M.2 slot with M key	M.2 slots with Type B or Type M keys
Common SSD models	No	Samsung XP941 (PCIe x4)	Most M.2 SATA SSDs Plextor M6e (PCIe x2)

There is one more problem. It lies in the fact that many motherboard developers ignore the requirements of the specifications and install the “coolest” slots with an M type key on their products, but only install two of the four assigned PCIe lanes on them. In addition, the M.2 slots available on motherboards may not be compatible with SATA drives at all. In particular, ASUS is guilty of installing M.2 slots with reduced SATA functionality. SSD manufacturers also adequately respond to these challenges, many of whom prefer to make both key cutouts on their cards at once, which makes it possible to physically install drives in M.2 slots of any type.

As a result, it turns out that to determine the real capabilities, compatibility and presence of the SATA interface in M.2 slots and connectors based on only one external signs impossible. That's why full information information about the implementation features of certain slots and drives can only be obtained from the passport characteristics of a particular device.

Fortunately, at the moment the range of M.2 drives is not so large, so the situation has not yet become completely confusing. In fact, there is currently only one model of M.2 drive with a PCIe x2 interface on the market - Plextor M6e - and one model with a PCIe x4 interface - Samsung XP941. All other flash drives available in stores in the M.2 form factor use the familiar SATA 6 GB/s protocol. Moreover, all M.2 SSDs found in domestic stores have two key cutouts - in positions B and M. The only exception is the 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 has support for M.2 PCIe drives, how many PCI Express lanes are connected to the M.2 slot?
• What arrangement of keys on the SSD card is allowed by the M.2 slot in the system?
• What is the maximum length of an M.2 card that can be installed in your motherboard?

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

Crucial M500

The Crucial M500 solid-state drive in M.2 format is an analogue of the well-known 2.5-inch model of the same name. There are no architectural differences between the “large” flash drive and its M.2 brother, which means we are dealing with inexpensive SSDs based on the popular Marvell 88SS9187 controller and equipped with 20nm flash memory manufactured by Micron with 128-gigabit cores . To fit the drive on an M.2 card, which measures only 22 × 80 mm, a tighter layout and flash memory chips with a denser packing of MLC NAND crystals are used. In other words, the Crucial M500 is unlikely to surprise anyone with its hardware design; everything about it is familiar and familiar for a long time.

We received two models for testing - with a capacity of 120 and 240 GB. As in 2.5-inch SSDs, their capacities turned out to be somewhat reduced relative to the usual multiples of 16 GB of volume, which means the presence of a larger reserve area, in this case occupying 13 percent of the total flash memory array. The M.2 versions of the Crucial M500 look like this:

Crucial M500 120 GB (CT120M500SSD4)

Crucial M500 240 GB (CT120M500SSD4)

Both drives are M.2 cards of 2280 format with keys of type B and M, that is, it can be placed in any M.2 slot. However, do not forget that the Crucial M500 (in any version) is a drive with a SATA 6 Gb/s interface, so it will only work in those M.2 slots that support SATA SSDs.

Both modifications of the drive in question carry four flash memory chips. On the 120 GB drive it is Micron MT29F256G08CECABH6, and on the 240 GB drive it is 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 interleaving of devices. This explains the noticeable differences in performance between Crucial M500 sizes. But both Crucial M500 modifications under consideration are equipped with the same amount of RAM. Both SSDs have a 256 MB DDR3-1600 chip installed.

It should be noted that one of the positive properties of Crucial consumer drives is hardware protection of data integrity in the event of sudden power outages. M.2 modifications of the Crucial M500 also have this property: despite the size of the board, flash drives are equipped with a battery of capacitors that allow the controller to normally complete its operation and save the address translation table in non-volatile memory even in cases of any excesses.

Crucial M550

Crucial was one of the first to embrace the new form factor, duplicating all of its consumer SSD models in both the traditional 2.5-inch format and in the form of M.2 cards. It is not surprising that after the appearance of M.2 versions of the M500, corresponding modifications of the newer and more powerful Crucial M550 model were released onto the market. The general approach to designing such SSDs has been preserved: in fact, we got a tracing paper from a 2.5-inch SATA model, but squeezed into the frame of an M.2-sized card. Therefore, from an architectural point of view, the M.2 version of the Crucial M550 is not at all surprising. This is a drive based on the Marvell 88SS9189 controller, which uses MLC NAND from Micron, manufactured according to 20 nm standards.

Let us remember 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 sought to give the flash memory array the maximum level of parallelism. Therefore, modifications of the Crucial M550 up to half a terabyte use MLC NAND with 64-gigabit cores.

For testing, we received a 128 GB Crucial M550 sample. This drive is an M.2 card of standard 2280 format, which is equipped with two keys of type B and M. This means that this drive can be installed in any slot, but for it to work, this slot must support the SATA interface, through which any version of Crucial works M550.

Crucial M550 128 GB (CT128M550SSD4)

The board of the Crucial M550 128 GB drive we received is interesting because all the chips on it are located on only one side. This allows it to be successfully used in ultra-thin portable systems in the so-called single-sided S2/S3 slots, where the rear surface of the drive's printed circuit board is pressed tightly against the motherboard. For most users, this does not matter, but, unfortunately, the struggle to reduce thickness resulted in the removal of capacitors from the drive, which provide an additional guarantee of data integrity in the event of sudden power outages. There are vacant places for them on the printed circuit board, but they are empty.

The entire 128-gigabyte Crucial M550 flash memory array is housed in two chips. Obviously, in this case, chips are used that contain eight 64-gigabit semiconductor crystals. This means that the Marvell 88SS9189 controller on the SSD model in question can use double interleaving of devices. A 256 MB LPDDR2-1067 chip is used as RAM.

The M.2 versions of the Crucial M550, like the Crucial M500 by the way, along with their more impressive-looking 2.5-inch brothers, support hardware data encryption using the AES-256 algorithm, which does not cause a decrease in performance. Moreover, it fully complies with the Microsoft eDrive specification, which means that you can manage flash memory encryption directly from Windows environment, for example using the standard BitLocker tool.

Kingston SM2280S3

Kingston has chosen a somewhat unconventional path to develop the niche of M.2 form factor solid-state drives. It did not release M.2 versions of its existing models, but designed a separate SSD, which has no analogues in other form factors. Moreover, the hardware platform chosen 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, the Kingston SM2280S3 is not something special: it is aimed at 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 board of the 2280 format. And since it works via the SATA 6 Gb/s interface, the blade connector of the drive has two key cutouts at once: type B and type M. That is, physically install the Kingston SM2280S3 it can be inserted into any M.2 slot, but for it to work it will require that this slot support a SATA interface.

In terms of hardware configuration, the Kingston SM2280S3 is similar to numerous 2.5-inch flash drives with a similar controller. Among them, we, for example, looked at Silicon Power Slim S55. Like the Silicon Power product, the Kingston SM2280S3 is equipped with flash memory manufactured by Toshiba. Although the chips installed on the SSD in question are relabeled, based on indirect evidence it can be said with a high degree of certainty that they use 64-gigabit MLC NAND crystals produced using a 19-nm process technology. Thus, the eight-channel Phison PS3108-S8 controller in the Kingston SM2280S3 can use double interleaving of devices in each of its channels. In addition, the SSD board also has a 256 MB DDR3L-1333 SDRAM chip, which is paired with the controller and is used by it as RAM.

An interesting feature of the Kingston SM2280S3: the manufacturer claims an extremely long service life for it. Official specifications allow daily recording of a volume of information on this SSD that is 1.8 times its capacity. True, performance in such harsh conditions is guaranteed only for three years, but this still means that up to 230 TB of data can be written to a 120 GB Kingston M.2 drive.

Plextor M6e

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

In other words, in the Plextor M6e we have a flagship device whose performance is not limited by the SATA 600 MB/s bandwidth. It is based on an eight-channel Marvell 88SS9183 controller, which transfers data from the SSD via two PCI Express 2.0 lines, which in theory allows for 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 MLC NAND from Toshiba, which is produced using the first generation 19nm process technology.

Our testing involved two versions of Plextor M6e in M.2 version: 128 and 256 GB.

Plextor M6e 128 GB (PX-G128M6e)

Plextor M6e 256 GB (PX-G256M6e)

Both M.2 drive options are located on cards measuring 22 × 80 mm. Moreover, please 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, was supposed to have only one type B key, the developers added a second key to it for compatibility . As a result, Plextor M6e can be installed in slots connected to four PCIe lanes, but this, of course, will not make the drive work faster. Therefore, M6e is primarily suitable for those M.2 slots that are found on many modern motherboards based on Intel H97/Z97 chipsets and are powered by a pair of PCIe chipset lines.

In addition to the Marvell 88SS9183 controller, the M6e boards have eight Toshiba flash memory chips. In the 128 GB version of the drive, these chips contain two 64-gigabit MLC NAND crystals, and in the 256 GB drive, each chip contains four similar cores. 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 also have 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.

Although using M.2 slots and PCI Express to connect SSDs is a relatively new trend, there are no compatibility issues with the Plextor M6e. Since they operate via the standard AHCI protocol, when they are installed in compatible M.2 slots (that is, those that support PCIe drives), they are detected in Motherboard BIOS boards along with regular disks. Accordingly, there are no problems in designating them as launch devices, and the operating system does not require special drivers for the M6e to work. In other words, these M.2 PCIe SSDs behave in exactly the same way as their M.2 SATA counterparts.

SanDisk X300s

SanDisk adheres to the same strategy as Crucial regarding M.2 drives - it repeats 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 made in the M.2 form factor - we are dealing with a drive based on a four-channel Marvell 88SS9188 controller and SanDisk proprietary MLC flash memory, manufactured using the second-generation 19-nm process technology.

Don’t forget that the 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 consolidation of write operations. This allows the X300s to provide decent performance despite its quad-channel controller architecture.

We were provided with a 256 GB SanDisk X300s sample for testing. He looked like this.

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

It is immediately noticeable that the drive board is single-sided, that is, it is also compatible with the “thin” M.2 slots that are used in some ultrabooks, allowing you to save an additional one and a half millimeters of thickness. Otherwise, there is 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. To operate, 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 it works according to the old rules and does not use the emerging possibilities of data transfer via the PCI Express bus.

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

The SanDisk X300s drive model is unique not only in its hardware architecture, which is based on a four-channel controller from Marvell. Focused on business use, it can offer enterprise-grade hardware data encryption that does not introduce any delays into the operation of the SSD. 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 two Transcend drives because, according to the manufacturer, they are almost completely identical in architectural terms. Indeed, they use a similar element base and claim the same performance indicators. The differences, according to the official version, lie only in the different sizes of M.2 cards on which they are assembled. The MTS600 and MTS800 are based on the proprietary Transcend TS6500 chip, which is actually a rebranded Silicon Motion SM2246EN controller. This means that the M.2 SSDs from Transcend that came to our tests are similar in their filling to the fairly popular 2.5-inch drive SSD370 offered by the same company. Thus, Transcend flash drives in M.2 format, like many other models participating in our testing, use the SATA 6 Gb/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 in mind that the Transcend MTS600 and MTS800 were designed. Together with a simple controller, these SSDs also use inexpensive 20nm flash memory with 128-gigabit cores from Micron, making the MTS600 and MTS800 one of the cheapest M.2 SSDs in today's testing.

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

Transcend MTS600 256 GB (TS256GMTS600)

Transcend MTS800 256 GB (TS256GMTS800)

It's a matter of 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 differs by as much as 2 cm. But the blade connector for both drives is the same and is equipped with two grooves in positions B and M. Accordingly, there are no mechanical compatibility restrictions, however, for these SSDs to work, the M.2 slot requires support for the SATA interface.

The boards of both drives are equipped with a Transcend TS6500 controller and a 256 MB DDR3-1600 SDRAM chip used as RAM. But the flash memory chips of the drives are unexpectedly different, which is clearly visible from their markings. The number and organization of these chips are the same: four chips, each containing 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 slightly lower latency. However, perhaps this is not due to some subtle marketing calculation, but to the fact that different batches of drives can have different memory installed.

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

⇡ Comparative characteristics of tested SSDs

	Crucial M500 120 GB	Crucial M500 240 GB	Crucial M550 128 GB	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 6 Gb/s	SATA 6 Gb/s	SATA 6 Gb/s	SATA 6 Gb/s	PCIe 2.0 x2	PCIe 2.0 x2	SATA 6 Gb/s	SATA 6 Gb/s	SATA 6 Gb/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 128Gb 20nm MLC NAND	Micron 64Gbit 20nm MLC NAND		Toshiba 64Gbit 19nm MLC NAND	Toshiba 64 Gbit 19 nm MLC NAND	SanDisk 64Gb A19nm MLC NAND	Micron 128Gb 20nm MLC NAND	Micron 128Gb 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	90000 IOPS	66000 IOPS	96000 IOPS	105000 IOPS	90000 IOPS	75000 IOPS	75000 IOPS
Random write speed	35000 IOPS	60000 IOPS	75000 IOPS	65000 IOPS	83000 IOPS	100000 IOPS	80000 IOPS	75000 IOPS	75000 IOPS
Record 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 methodology

Testing is carried out in the Microsoft Windows 8.1 Professional x64 with Update operating system, which correctly recognizes and services modern solid-state drives. This means that during the testing process, as in normal everyday use of the SSD, the TRIM command is supported and actively used. Performance measurements are performed with drives in a “used” state, which is achieved by pre-filling them with data. Before each test, the drives are cleaned and maintained using the TRIM command. There is a 15-minute pause between individual tests, allotted for the correct development of garbage collection technology. All tests, unless otherwise noted, use random incompressible data.

Applications and tests used:

• Iometer 1.1.0

1. Measuring the speed of sequential reading and writing data in blocks of 256 KB (the most typical block size for sequential operations in desktop tasks). The speeds are estimated within a minute, after which the average is calculated.
2. Measuring the speed of random reading and writing in 4 KB blocks (this block size is used in the vast majority of real-life 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 memory pages of the drives. The speed assessment is performed for three minutes, after which the average is calculated.
3. Establishing the dependence of random read and write speeds when operating a drive with 4 KB blocks on the depth of the request queue (ranging from one to 32 commands). Data blocks are aligned relative to the flash memory pages of the drives. The speed assessment is performed for three minutes, after which the average is calculated.
4. Establishing the dependence of random read and write speeds when the drive operates with blocks of different sizes. Blocks ranging in size from 512 bytes to 256 KB are used. The request queue depth during the test is 4 commands. Data blocks are aligned relative to the flash memory pages of the drives. The speed assessment is performed for three minutes, after which the average is calculated.
5. Measuring performance under mixed multi-threaded workloads and determining its dependence on the ratio between read and write operations. Sequential read and write operations of 128 KB blocks are used, performed in two independent threads. The ratio between read and write operations varies in 10 percent increments. The speed assessment is performed for three minutes, after which the average is calculated.
6. Study of SSD performance degradation when processing a continuous stream of random write operations. Blocks of 4 KB in size and a queue depth of 32 commands are used. Data blocks are aligned relative to the flash memory pages of the drives. 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 operation of garbage collection technology and after running the TRIM command.

• CrystalDiskMark 3.0.3b
  A synthetic test that provides typical performance indicators for solid-state drives, measured on a 1-gigabyte disk area “on top” of the file system. Of the entire set of parameters that can be assessed using this utility, we pay attention to the speed of sequential read and write, as well as the performance of random read and write of 4 KB blocks without a request queue and with a queue depth of 32 commands.
• PCMark 8 2.0
  A test based on emulating real disk load, which is typical for various popular applications. On the drive being tested, a single partition is created in the NTFS file system for the entire available volume, and the Secondary Storage test is run in PCMark 8. The test results take into account both the final performance and the execution speed of individual test traces generated by various applications.
• File copy tests
  This test measures the speed of copying directories with different types of files, as well as the speed of archiving and unzipping files inside the drive. Used for copying standard remedy Windows - Robocopy utility, when archiving and unzipping - 7-zip archiver version 9.22 beta. The tests involve three sets of files: ISO - a set that includes several disk images with program distributions; Program - a set that is a pre-installed software package; Work - a set of work files, including office documents, photographs and illustrations, pdf files and multimedia content. Each set has a total file size of 8 GB.

⇡ Test stand

A computer with a motherboard is used as a test platform ASUS board Z97-Pro Core processor i5-4690K with integrated Intel HD Graphics 4600 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 serviced by dialing tools Intel logic Z97 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 second connection option, the capabilities of this slot are quite sufficient in the context of this testing. The operation of solid-state drives in the operating system is ensured Intel driver Rapid Storage Technology (RST) 13.2.4.1000.

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

⇡ Test participants

The full list of M.2 drives that took part in this comparison is as follows:

• Crucial M500 120 GB (CT120M500SSD4, firmware MU05);
• Crucial M500 240 GB (CT120M500SSD4, firmware MU05);
• Crucial M550 128 GB (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 reads and writes

It must be said right away that since drives in M.2 format 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 conventional SSDs. In particular, the sequential read speed, as is usually the case, approaches the interface bandwidth, and in this parameter both modifications of the Plextor M6e, which operate via the PCIe x2 bus, are ahead.

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

Random reads

It is curious that when measuring random read performance, the Plextor M6e 256 GB, equipped with a PCIe x2 interface, yields first place to the SanDisk X300s 256 GB flash drive, which has efficient nCache technology. In other words, it turns out that M.2 SSDs using a SATA connection can compete on equal terms with PCIe x2 models, at least with those that are currently on the market. By the way, among solid-state drives with a capacity of 128 GB, 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 4 KB blocks.

As the depth of the request queue increases, Plextor drives still take the lead, but it should be understood that in real tasks this depth rarely exceeds four commands. The same graph clearly shows the weaknesses of those SSDs that are built on four-channel controllers. As the load increases, their results scale much worse, so such products should not be used in applications that require processing complex multi-threaded requests.

In addition to this, we suggest looking at how the random read speed depends on the size of the data block:

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

Random writes

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

The entire dependence of the speed of random writing in 4-kilobyte blocks on the depth of the request queue is as follows:

The Crucial M550 delivers superior performance at all but maximum queue depths. But drives from the same manufacturer, but from the previous M500 line, on the contrary, are characterized by extremely low speed when writing data.

The following graph shows random write performance as a function of data block size.

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

As SSDs become cheaper, they are no longer used as purely system drives and are becoming regular work drives. In such situations, the SSD receives not only a 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 remains a significant problem for modern SSD controllers. When mixing reads and writes in the same queue, the speed of most consumer-grade SSDs noticeably drops. This became the reason for conducting a separate study, in which we check how SSDs work when it is necessary to process sequential operations arriving interspersed. The following chart shows the most typical case for desktops, where the ratio of read to write operations is 4 to 1.

Both Plextor M6e hold the lead here. They are strong at sequential read operations and mixing in some small share of write operations 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 loads.

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

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

PCMark 8 2.0, real use cases

The Futuremark PCMark 8 2.0 test package is interesting because it is not of a synthetic nature, but, on the contrary, is based on the work of real applications. During its passage, real scenarios of using the disk in common desktop tasks are reproduced and the speed of their execution is measured. Current version This test simulates a workload that is taken from real game applications of 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 that the drives show when passing test routes.

The first two places in PCMark 8 are won by Plextor M6e with a capacity of 128 and 256 GB. It turns out that when actually working in applications, these drives strong point which use not the SATA interface, but PCIe x2, are still superior to other M.2 SSDs based on architecture borrowed from 2.5-inch models. And among the noticeably cheaper SATA models, the best performance is given by 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 performance indicators produced by flash drives when passing individual test traces that simulate various real-life load options. The fact is that under different loads, flash drives often behave slightly differently.

Plextor drives show excellent performance in any application 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 the Plextor M6e is capable of delivering unattainable speeds, but to the fact that among the M.2 SATA SSD models we received for testing there were no, for example, Samsung offers or new Crucial drives that are quite capable of competing in speed with a Plextor M6e drive running via PCIe x2.

Copying files

Keeping in mind that solid-state drives are being introduced into personal computers more and more widely, we decided to add to our methodology a measurement of performance during common file operations - when copying and working with archivers - which are performed “inside” the drive. This is a typical disk activity that occurs when the SSD acts not as a system drive, but as a regular disk.

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

The second group of tests was carried out when archiving and unarchiving a directory with working files. The fundamental difference in this case is that half of the operations are performed with separate files, and the second half with one large archive file.

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

How TRIM and Background Garbage Collection Work

When testing various SSDs, we always check how they handle the TRIM command and whether they are able to collect garbage and restore their performance without support from the operating system, that is, in a situation where the TRIM command is not issued. Such testing was carried out this time as well. The design of this test is standard: after creating a long continuous load on writing data, which leads to write speed degradation, 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 forced onto the drive - and after a short pause, the speed is measured again.

The results of such testing are shown in the following table, which indicates for each model tested whether it responds to TRIM by clearing unused portions of flash memory and whether it can prepare blank pages flash memory for future operations if the TRIM command is not issued to it. For drives that were able to perform garbage collection without the TRIM command, we also indicated the amount of flash memory that was independently freed by the SSD controller for future operations. If the drive is used in an environment without TRIM support, this is exactly the amount of data that can be saved to the drive with a high initial speed after idle time.

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

All M.2 drives that have passed our testing process the TRIM command normally. And it would be strange if in 2015 one of the SSDs suddenly could not cope with such, one might say, a basic function. But with a more complex task—garbage collection without support from the operating system—the situation is different. The most effective algorithms that allow you to proactively release the largest amount of flash memory for future recordings are the Kingston SM2280S3 based on the Phison S8 controller and the 256 GB Plextor M6e with a Marvell 88SS9183 controller. Interestingly, the 128GB version of the Plextor PCIe drive performs garbage collection much less efficiently. However, in any case, almost all of the tested drives, when idle, reorganize data in flash memory and prepare it for the rapid execution of subsequent operations. There is only one exception - SanDisk X300s 256 GB, for which garbage collection does not work at all without TRIM.

It should be recalled that for modern solid-state drives the need for garbage collection operating without TRIM can be questioned. All current versions of common operating systems support TRIM, so consider that SanDisk X300s, in which offline garbage collection does not work, is fundamentally worse than others featured in this SSD review, would be incorrect. In everyday use, this feature is unlikely to manifest itself in any way.

⇡ Conclusions

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

In theory, the M.2 standard does indeed offer greater capabilities compared to other types of connections. And the point here is not only that M.2 cards are compact, have a size convenient for accommodating 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 promising 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 whose maximum speed is not limited to 600 MB/s and data exchange with which is not necessary executed using the AHCI protocol with high overhead.

Another thing is that in practice all this splendor is not yet fully revealed. The M.2 drive models available today are for the most part based on exactly the same architecture as their 2.5-inch counterparts, which means they work through the same tired SATA interface. Almost all of the SSDs in the M.2 form factor that we reviewed turned out to be analogues of some model of the usual format, and therefore they offer characteristics that are completely typical for mass-produced solid-state drives, including the level of performance. The only original M.2 drive among the products available in domestic stores is only the Plextor M6e, which operates via the PCIe x2 interface, thanks to which it shows better speed for sequential operations than all its competitors. But even it cannot be called an ideal SSD in the M.2 format: the Plextor M6e uses a relatively weak controller, which causes its low performance under random access workloads.

So should you strive to fill the M.2 slot with an SSD if your motherboard has one? If we do not take into account those mobile configurations that other SSD options simply do not allow, then, frankly speaking, now there are no obvious arguments in favor of a positive answer to this question. However, we also cannot give negative arguments. In fact, by purchasing and installing an M.2 SSD into your system, you will get approximately the same as if you were using a standard 2.5-inch SATA SSD. At the same time, M.2 cards on average cost a little more than full-size drives (sometimes the opposite is true), 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 to decide.

But if you ultimately decide to purchase an SSD in the M.2 form factor, then from among the options available for sale, we recommend paying attention to the following models:

• Plextor M6e. The only M.2 drive available in domestic retail with a PCIe 2.0 x2 interface. Due to the increased interface bandwidth, it demonstrates high speeds in sequential operations, making it a high-performance solution for some real-world workloads. Unfortunately, the cost of such an SSD is noticeably higher than that of models operating via SATA.
• Crucial M550. An excellent 2.5-inch drive has an analogue in M.2 format that is almost no different from it. Compact versions of the Crucial M550 are just as fast and omnivorous as the full-size flash drives of the same name, and the only feature that was lost when moving to M.2 was hardware-based data integrity protection against 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 productive as 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 perhaps offers the most favorable price-performance ratio among all the models tested. This is what makes it interesting - it is a very worthy solution for inexpensive platforms.

Maybe now everyone knows that SSDs are very fast and get along very well with the operating system, which makes it a "smoke". Of course, many of you have already bought an SSD and are enjoying the speed and response time.
Today you will see an SSD that looks like an M.2, which is installed directly on the motherboard or laptop with a free M.2 slot.

What is M.2?
M.2 slot that can connect SSD drives and other wireless network cards.
Currently M.2 comes in two versions:
1. SATA M.2
2. M.2 PCI-Express

Attention!
1. Before you buy an SSD, check which M.2 type you have. Just go to M.2 SATA SSD M.2 SATA and PCI-E SSD M.2 just go PCI-E.
2. M.2 SATA SSD drives come in different sizes. SSD tutorial 2280, which is 22mm by 80mm width and length. There may be one more aspect printed on your laptop or your motherboard (30, 42, 60 or 110 millimeters).
3. Not all laptops and motherboards have an M.2 slot. Usually the latter can, but not necessarily.

SSD speed testing was no competition. SSHD is not too slow for an SSD. In addition to that, M.2 SSDs did not incur any path speed penalty; What's more, this MX200 Crucial SSD is faster than the desktop.
Although very slow, HDD or SSHD have an advantage large capacity, providing storage capacity at a low cost. It certainly won't take too long. Technology has taken a fantastic course in recent years, and it is possible that in the near future it will be cheaper to have 2-3 TB SSDs than hard disks, since technically, SSDs are produced faster and cheaper when it scales production.
SSD advantages of M.2?
1. Very compact format
2. Lack of data and power cables
3. Speed ​​comparable to 2.5 SSDs
4. Ideal for laptops/tablets
5. SSDs are M.2 PCI-E SATA 5 times faster

Video Tutorial - Installing M.2 SSD and SSD performance difference compared to SSHD
M.2 SSDs - prices voucher I1I7YG41

The different types of keys are marked on or near the end contacts (gold plated) of the M.2 SSD, as well as on the M.2 connector.

The illustration below shows M.2 SSD keys on M.2 SSDs and compatible M.2 slots with slots to allow the drives to be inserted into the appropriate slots:

Please note that M.2 SSDs with B key have a different number of end pins (6) compared to M.2 SSDs with M key (5); This asymmetrical design avoids the mistakes of placing an M.2 SSD with key B in slot M, and vice versa.


What do the different keys mean?

M.2 SSDs with Key B end pins can support SATA and/or PCIe protocol depending on the device, but are limited by the speed of PCIe x2 (1000MB/s) on the PCIe bus.

M.2 SSDs with M key end pins can support SATA and/or PCIe protocol depending on the device, and support PCIe x4 speeds (2000MB/s) on the PCIe bus if the host system also supports x4 mode.

M.2 SSDs with B+M key end contacts can support SATA and/or PCIe protocol depending on the device, but are limited to x2 speeds on the PCIe bus.

More details

Which M.2 and connector configurations are not compatible?



SSD Key M.2 Key B Key M
SSD end contacts SSD edge connector - B Key SSD edge connector - M Key
Incompatible connectors Not Compatible Sockets - B Key Not Compatible Sockets - M Key

What are the benefits of having a B+M key on an M.2 SSD?

B+M keys on M.2 SSDs provide cross-compatibility with various motherboards, as well as support for the corresponding SSD protocol (SATA or PCIe). Host connectors of some motherboards can be designed to connect only SSDs with M keys or only with B keys. SSDs with B+M keys are designed to eliminate this problem; however, plugging an M.2 SSD into the slot does not guarantee it will work, it depends on the overall protocol between the M.2 SSD and the motherboard.


What types of M.2 SSD host connectors are found on motherboards?

M.2 host connectors can be B-key based or M-key based. They can support both the SATA protocol and the PCIe protocol. Conversely, they can only support one of the two protocols.

If the SSD terminal pins are B+M keyed, they will physically fit into any host connector, but you must check the motherboard/system manufacturer's specifications to ensure protocol compatibility.


How do I know what length of M.2 SSD my motherboard supports?

You should always check your motherboard/system manufacturer's information to check which card lengths are supported, however most motherboards support 2260, 2280 and 22110. Many motherboards have a removable retaining screw allowing the user to install a 2242, 2260, 2280 or even 22100 M.2 SSD . The amount of space on the motherboard limits the size of M.2 SSDs that can be installed in the slot and used.


What does "socket 1, 2 or 3" mean?

Different connector types are part of the specification and are used to support special types of devices in a connector.

Socket 1 is designed for Wi-Fi, Bluetooth®, NFC and WI Gig

Socket 2 is designed for WWAN, SSD (cache memory) and GNSS

Socket 3 is for SSD (SATA and PCIe, speed up to x4)


Does Socket 2 support both WWAN and SSD?

If the system does and does not use Socket 2 to support a WWAN card, it can be used for an M.2 SSD (usually a compact form factor such as 2242) if it has a B key. M.2 SATA SSDs can be inserted into WWAN compatible slots , if the motherboard supports it. Typically, low-capacity M.2 2242 SSDs are used for caching along with a 2.5-inch hard drive. In any case, you should review the system documentation to verify M.2 support.


Is it possible to hot-plug an M.2 SSD?

No, M.2 SSDs are not hot-pluggable. Installation and removal of M.2 SSDs is only allowed when the system is powered off.


What are single-sided and double-sided M.2 SSDs?

For some space-constrained embedded systems, M.2 specifications provide varying thicknesses of M.2 SSDs—3 single-sided versions (S1, S2, and S3) and 5 double-sided versions (D1, D2, D3, D4, and D5). Some platforms may have specific requirements due to space limitations under the M.2 connector, see image below (Property of LSI).


Kingston's SSDM.2 meets the specifications of dual-sided M.2 and can be installed in most motherboards compatible with dual-sided M.2 SSDs; Contact your sales representative if you require single-sided SSDs for embedded systems.


What's planned for the future?

The next generation of M.2 PCIe SSDs will move away from using the older AHCI drivers currently built into operating systems to a new architecture using the new Non-Volatile Memory Express (NVMe) host interface. NVMe was designed from the start to support NAND-based SSDs (and possibly newer persistent memory) and delivers even higher levels of performance. Preliminary production testing shows its speeds to be 4 to 6 times faster than current SATA 3.0 SSDs.

It is expected that it will begin to be implemented in 2015 in the corporate sphere, and then transferred to client systems. As the industry prepares the ecosystem for the release of NVMe SSDs, beta drivers already exist on many operating systems.