M.2 SSD vs Sata SSD, difference beyond size & connectivity


  • M.2 SSD 

    An M.2 SSD is a solid-state drive (SSD) that conforms to a computer industry specification written for internally mounted storage expansion cards of a small form factor. The specification, originally known as the Next-Generation Form Factor (NGFF), is pronounced M-dot-2.

    M.2 SSDs are designed to enable high-performance storage in thin, power-constrained devices, such as ultrabook and tablet computers. They are generally smaller than mSATA SSDs, for which they are intended as an alternative.

    The M.2 form-factor specification was defined by the PCI Special Interest Group (PCI-SIG) consortium of technology industry vendors and the Serial ATA International Organization. The M.2 specification supports applications such as Wi-Fi, Universal Serial Bus (USB), PCI Express (PCIe) and Serial ATA (SATA).

    SATA M.2 is described in the SATA v3.2 Specification.

    M.2 SSD vs. mSATA

    M.2 is commonly referred to as an mSATA replacement, but mSATA SSDs still exist and will probably continue for some time in laptop platforms that support that form factor. Because M.2 and mSATA cards are different form factors and have different connectors, they cannot be plugged into the same devices. M.2 SSDs are faster and store more data than most mSATA cards. M.2 SSDs support PCIe 3.0, SATA 3.0 and USB 3.0 interfaces, while mSATA only supports SATA. M.2 SATA SSDs have similar performance to mSATA cards, but M.2 PCIe cards are faster. SATA SSDs have a maximum speed of 600 MB per second, while M.2 PCIe cards can hit 4 GB per second.

    PCIe support also allows M.2 cards to take advantage of the nonvolatile memory express (NVMe) protocol, which brings a large performance advantage over other types of interfaces due to reduced latency, increased IOPS and lower power consumption.

     
    This video from ASUS North America 
    explains M.2, SATA, PCIe and NVMe 
    SSDs.

    As of early 2017, the largest M.2 SSDs support 1 TB of capacity, more than any mSATA drives. M.2 connectors support four lanes of PCIe bandwidth, or one SATA or USB lane.


    M.2 SSD form factor

    M.2 SSDs are rectangular. They are 22 millimeters (mm) wide and usually 60 mm or 80 mm long, although there are also 30 mm, 42 mm and 110 mm length cards. Longer length M.2 drives usually hold more NANDchips for extra capacity than the shorter versions. M.2 drives can be single or double-sided. The card size is identified by a four- or five-digit number. The first two digits are the width and the remaining numbers are the length. For example, a 2260 card is 22 mm wide and 60 mm long.

    The 22 mm width is standard for desktop and laptops. An 80 mm or 110 mm length card can hold 8 NAND chips for 1 TB of capacity.