A solid-state drive (SSD, also known as a solid-state disk is a solid-state storage device that uses integrated circuit assemblies as memory to store data persistently. SSD technology primarily uses electronic interfaces compatible with traditional block input/output (I/O) hard disk drives (HDDs), which permit simple replacements in common applications. Additionally, new I/O interfaces, like SATA Express and M.2 have been designed to address specific requirements of the SSD technology.
SSDs have no moving mechanical components. This distinguishes them from traditional electromechanical magnetic disks such as hard disk drives (HDDs) or floppy disks, which contain spinning disks and movable read/write heads. Compared with electromechanical disks, SSDs are typically more resistant to physical shock, run silently, have lower access time, and lower latency. However, while the price of SSDs has continued to decline over time, consumer-grade SSDs are (as of 2016) still roughly four times more expensive per unit of storage than consumer-grade HDDs.
As of 2015, most SSDs use MLC NAND-based flash memory, which is a type of non-volatile memory that retains data when power is lost. For applications requiring fast access but not necessarily data persistence after power loss, SSDs may be constructed from random-access memory (RAM). Such devices may employ batteries as integrated power sources to retain data for a certain amount of time after external power is lost.
M.2 (pronounced M dot two), formerly known as the Next Generation Form Factor (NGFF). The Intel come with new version of the SSD. It was one of the first PCIe based SSDs to support the wide and fast PCIe 3.0 x4 interface and also the NVMe protocol. NVMe (or Non-Volatile Memory Express) was developed expressly for PCIe-based SSDs, and supersedes the old AHCI protocol (The Advanced Host Controller Interface AHCI it gives software developers and hardware designers a standard method for detecting, configuring, and programming SATA/AHCI adapters. AHCI is separate from the SATA 3 Gbit/s standard), with the goal to improve storage performance. The SSD 750 Series is available in two form factors: a standard half-height, half-length add-in card, and also a 2.5-inch form factor that utilizes the new U.2 connector. A note about U.2 connectors; they are only found on selected motherboards, so you may need an M.2 to U.2 connector if you do optimisation for the 2.5-inch form factor. The add-in card version features a large and chunky silver heatsink that covers the entire length of the PCB board, whereas the 2.5-inch version looks like a thicker version of any other SATA-based SSD. Since the Intel SSD 750 Series is based heavily on the SSD DC P3700, it is not surprising to see the same mega 18-channel Intel controller as its enterprise counterpart. This controller is Intel’s own design and its 18 NAND channels give it a huge advantage over most client-grade SSD controllers, which only have an 8-channel design. However, one feature notably missing is support for hardware encryption. While the controller is likely to offer better performance, it also suffers from high power consumption. According to figures from Intel, active and idle power draw for the smaller 400GB model can be as high as 12W and 4W, respectively, with no support for DevSlp (SATA Device Sleep). In comparison, most SSDs with support for DevSlp can have idle power consumption figures as low as 3mW. The NAND in use in the SSD 750 Series is Micron’s 20nm MLC NAND. The SSD 750 Series is available in 400GB, 800GB and 1.2TB capacities. The reason for these conventional ampacities is because a large amount of NAND is dedicated to over-provisioning. The drive comes with a half-height installation bracket, a CD containing Intel’s own NVMe driver, and also Intel’s SSD Toolbox utility. This utility lets users monitor and check on the drives’ status and also quickly update its firmware when they become available.
M.2's more flexible physical specification allows different module widths and lengths, and, paired with the availability of more advanced interfacing features, makes the M.2 more suitable than mSATA for solid-state storage applications in general and particularly for the use in small devices such as ultrabooks or tablets.