Working in the Tech Industry I see a lot of people who get confused about certain technologies and the difference between one technology and another.
One of the biggest confusions that I see is around M.2 (NGFF-Next Generation Form Factor) drives. There are different types and sizes of M.2 drives, and they aren’t all cross-compatible.
There are two main types of M.2 drive: AHCI and NVMe. The sizes and even connector types can sometimes differ between these types, but the biggest difference is the interface the drive uses.
AHCI (Advance Host Controller Interface) drives use SATA technology to interact with a computer. While they use NGFF, they behave similarly to 2.5″ SATA SSDs in performance as well as connectivity.
These drives can be easily adapted to many other interfaces because of this. Many of the M.2 to USB or M.2 to SATA adapters are designed specifically for AHCI M.2 drives, and will not work with their NVMe counterpart.
NVMe drives are a combination of two specifications: NVMHCIS (Non-Volatile Memory Host Controller Interface Specification) and PCIe (Peripheral Component Interconnect Express). Simply put, these drives use a PCIe bus interface for non-volatile memory storage.
Unlike AHCI M.2 drives, NVMe requires a PCIe interface to work. This can cause some issues, especially when being used with adapters designed solely for AHCI. Because the drive interfaces directly with PCIe (and uses 4 lanes) the speed of NVMe drives greatly out-perform AHCI drives. This makes NVMe one of the fastest consumer level drives available.
Many new laptops are shipping with NVMe drives, as they make the operating system lightning-fast and the performance loss over time is decreased compared to platter drives. When this first started happening there were problems with laptop maintenance since the drives couldn’t be read unless they were in a computer that natively supported NVMe M.2, which was a new technology at the time.
We’re now starting to see adapters that use Thunderbolt 3 or U.2 (both which use PCIe lanes) to allow using NVMe M.2 drives with systems that don’t natively support the interface. This still bars people who do not have U.2 or Thunderbolt 3 available, but it does open up the possibilities with NVMe drives a little further.
While more accessible adapter options may be in the works, NVMe drives are quickly being adopted as the recommended boot drive interface for PC enthusiasts.