SSDs2024-07-01
M.2 SSDs: Big Performance Comes in Small Packages
Solid state drives
(SSDs) released in recent years have become faster and more 0️⃣ capable of handling large
amounts of data. Their full capabilities, however, are being hindered or limited by the
interfaces they 0️⃣ are connected to. Serial ATA 3rd generation interfaces, designed for
the much slower mechanical hard disk drives, run with a 0️⃣ maximum native transfer rate of
6 Gb/s.
The Mini-SATA (mSATA) interface, though designed specifically to provide the
smallest form factor for 0️⃣ SSDs, is limited by the SATA 6 Gb/s link. The M.2 standard, a
specification for internally mounted computer add-in cards, 0️⃣ was created to address the
limitations of mSATA and provide more options for small form factor cards, including
SSDs in 0️⃣ different sizes and with different capacities. M.2 was originally called the
Next Generation Form Factor (NGFF), and then formally renamed 0️⃣ to M.2 in 2013. M.2
improves on the mSATA standard, which uses the PCI Express® Mini Card physical card
layout 0️⃣ and connectors. As mSATA's "successor," M.2 provides higher performance and
capacity while minimizing module footprint.
An M.2 SSD module is connected 0️⃣ to a host
either through a SATA interface or via a PCI Express (PCIe) lane. Though M.2 supports
both SATA 0️⃣ and PCIe, an M.2 module may only be inserted in either one of the two
interfaces, so check your motherboard 0️⃣ documentation to make sure that your module fits
and works with the corresponding socket on the motherboard.
Differences Between an M.2
0️⃣ and mSATA SSD
Both are high-performance SSDs designed for small devices such as laptops
and tablets. The mSATA interface used to 0️⃣ provide the smallest form factor for SSDs.
However, it is limited by the SATA 3.0 link speed of 6 Gb/s 0️⃣ and 1 TB maximum capacity.
The M.2 form factor was borne out of the need for multiple options for small 0️⃣ form
factor cards, including SSDs in different sizes and with different capacities, and
possibilities for extending capacities even further. M.2 0️⃣ provides higher performance
while minimizing module footprint. M.2 SSDs come in longer modules and with
double-sided component population, enabling larger 0️⃣ storage capacities within minimal
spaces. It requires no power or data cables, making installation complete without the
need for cable 0️⃣ management.
M.2 SSDs support both SATA and PCIe interfaces. The SATA
revision 3.2 specification, in its gold revision as of August 0️⃣ 2013, standardizes the
SATA version of M.2 as a new format for storage devices and specifies its hardware
layout. For 0️⃣ the PCIe version, details are included in the PCI-SIG M.2 Specification
Rev. 1.1.
Physically, they look different and cannot be plugged 0️⃣ into the same sockets.
The pictures below show ATP M.2 and mSATA SSDs.
SATA or NVMe?
SATA remains one of the
most 0️⃣ widely used interfaces in industrial and enterprise applications, so M.2 SATA
modules are optimal choices for those who want compatibility 0️⃣ with existing systems as
well as the convenience of hot-swapping and hot-plugging. M.2 modules designed for a
SATA interface will 0️⃣ perform according to the latest SATA 3rd generation standard, which
is up to 6 Gb/s.
Enterprises and client systems with a 0️⃣ greater need for speed can take
advantage of the Non-Volatile Memory Express or NVM Express® (NVMe™), an interface
specification developed 0️⃣ specifically for NAND flash and next-generation SSDs. NVMe
leverages existing PCIe technology to efficiently support the growing bandwidth needs
of 0️⃣ enterprise and client systems. An NVMe-based M.2 SSD module installed on a PCIe x2
lane will run at 15.75 Gb/s, 0️⃣ while a module installed on a PCIe x4 lane will run at
31.5 Gb/s – a massive leap in speed 0️⃣ and performance.
An M.2 SSD module is designed only
for either a SATA or PCIe interface, not both at the same 0️⃣ time, although some systems
may have M.2 sockets that will support either one or both interfaces.
ATP offers both
M.2 SATA 0️⃣ and PCIe solutions. ATP NVMe SSDs are designed for a PCIe 3.0 x4
interface.
Size Matters
M.2 modules come in different sizes 0️⃣ and can also be utilized
for Wi-Fi, WWAN, Bluetooth, GPS, and NFC.
M.2 SSDs typically come in three dimensions,
which may 0️⃣ be deduced from the card name —2242, 2260, and 2280 — "22" represents the
width in millimeters (mm), while the 0️⃣ next two digits represent the length, also in mm.
The longer the drive, the more NAND flash chips can be 0️⃣ mounted; hence, more
capacity.
In choosing the right size, one has to consider how many SSDs can be packed
into a 0️⃣ chassis, as well as thermal management issues, which may be a significant factor
for sustained performance. If the area for 0️⃣ dissipating heat is insufficient, it may
result to poor performance and instability in the long run.
The picture below shows ATP
0️⃣ M.2 SSDs in different lengths.
Keys and Sockets
An M.2 SSD is "keyed" to prevent
insertion of a card connector (male) to 0️⃣ an incompatible socket (female) on the host.
The M.2 specification identifies 12 key IDs on the module card and socket 0️⃣ interface but
M.2 SSDs typically use three common keys: B, M, and B+M. You will find the key type
labeled 0️⃣ on or near the edge connector (or gold fingers) of the SSD. Before deploying
M.2 SSDs, determine the type of 0️⃣ socket on the host and check the module connector
keying, as each connector should be inserted only in the appropriate 0️⃣ socket.
ATP M.2
SATA SSDs are B+M-keyed (can fit in sockets for B-keyed and M-keyed modules), while M.2
NVMe SSDs for 0️⃣ PCIe 3.0 x4 lane are M-keyed.
Key ID Pin Location Interface A 8-15 2x
PCIe x1 / USB 2.0 / I2C 0️⃣ /
DP x4 B 12-19 PCIe x2 / SATA /USB 2.0 / USB 3.0 / HSIC / SSIC
/ Audio / 0️⃣ UIM / I2C C 16-23 Reserved for Future Use D 20-27 Reserved for Future Use E
24-31 2x PCIe x1 0️⃣ / USB 2.0 / I2C / SDIO /
UART / PCM F 28-35 Future Memory Interface
(FMI) G 39-46 Not Used 0️⃣ for M.2; for Custom/Non-Standard Apps H 43-50 Reserved for
Future Use J 47-54 Reserved for Future Use K 51-58 Reserved 0️⃣ for Future Use L 55-62
Reserved for Future Use M 59-66 PCIe x4 / SATA
Table 1. Module key IDs, pin 0️⃣ locations
and interfaces.
Source: "All About M.2 SSDs," Storage Networking Industry Association
(SNIA). 2014.
M.2 connectors on the host are called "sockets." 0️⃣ Each socket has a unique
mechanical key, and modules are not interchangeable between sockets. According to PCI
Express M.2 Specifications 0️⃣ Rev. 1.1, the sockets are distinguished as follows:
Socket 1
: Connectivity socket for Wi-Fi ® , Bluetooth ® , NFC 0️⃣ (near-field communication) or
Wi-Gig.
Socket 2 : WWAN/SSD/Other Socket that will support various WWAN+GNSS (global
navigation satellite system) solutions, various SSD 0️⃣ and SSD Cache configurations, and
other yet-undefined solutions. (If the motherboard has a Socket 2 for a WWAN card and
0️⃣ it is not in use, the socket may accommodate a B+M-keyed small M.2 SSD. Please refer to
your motherboard documentation 0️⃣ for details).
Socket 3 : SSD Drive Socket with SATA or
up to four PCIe lanes.
Important Notes:
Please refer to your motherboard 0️⃣ documentation
to make sure that your M.2 module fits and works with the corresponding socket on the
motherboard.
M.2 modules are 0️⃣ neither hot-swappable nor hot-pluggable. Performing
hot-swap or hot-plug may damage the modules and cause harm to the person performing
this 0️⃣ .
Conclusion
As SSDs continue to revolutionize the way enterprises handle data,
choosing the right storage media in the right form factor 0️⃣ and their corresponding
interfaces will be critical. M.2 SSDs offering smaller, faster and more efficient
storage enlarge the range of 0️⃣ choices and solutions to match workloads with price and
performance.
For more information on ATP's M.2 SSDs, visit the ATP website 0️⃣ or contact
an ATP Distributor/Representative in your area.
