NVM Express (NVMe) or Non-Volatile Memory Host Controller Interface Specification (NVMHCIS) is an open, logical-device interface specification for accessing a computer’s non-volatile storage media usually attached via PCI Express (PCIe) bus. The acronym NVM stands for non-volatile memory, which is often NAND flash memory that comes in several physical form factors, including solid-state drives (SSDs), PCI Express (PCIe) add-in cards and M.2 cards, the successor to mSATA cards. NVM Express, as a logical-device interface, has been designed to capitalize on the low latency and internal parallelism of solid-state storage devices.
M.2, formerly known as the Next Generation Form Factor (NGFF), is a specification for internally mounted computer expansion cards and associated connectors. M.2 replaces the mSATA standard, which uses the PCI Express Mini Card physical card layout and connectors. Employing a more flexible physical specification, the M.2 allows different module widths and lengths, and, paired with the availability of more advanced interfacing features, makes the M.2 more suitable than mSATA in general for solid-state storage applications, and particularly in smaller devices such as ultrabooks and tablets.
Serial ATA (SATA, abbreviated from Serial AT Attachment) is a computer bus interface that connects host bus adapters to mass storage devices such as hard disk drives, optical drives, and solid-state drives. Serial ATA succeeded the earlier Parallel ATA (PATA) standard to become the predominant interface for storage devices.
Serial ATA industry compatibility specifications originate from the Serial ATA International Organization (SATA-IO) which are then promulgated by the INCITS Technical Committee T13, AT Attachment (INCITS T13).
One of the bigger breakthroughs for PC hardware in modern memory has been the solid state drive. And with data transfer speeds many multiples of traditional 7200 RPM and even 10,000 RPM drives, it’s easy to see why. Not only are boot and shut down speeds much faster with SSDs, but all aspects of the system are sped up as well. But what about NVMe SSDs, how do they differ from standard SATA drives? And do all M.2 drives classify as NVMe?
What is NVMe?
First, a quick note about SSDs – they’re fast. So fast in fact, their limiting factor is not their own hardware, but rather the SATA III connection that hard drives have traditionally used. Enter NVMe. Standing for “Non-Volatile Memory Express,” NVMe is an open standard developed to allow modern SSDs to operate at the read/write speeds their flash memory is capable of.
Basically, it allows flash memory to operate as an SSD directly through the PCIe interface rather than going through SATA and being limited by the slower SATA speeds. Put another way, it’s a description of the bus the component uses to communicate with the PC, not a new type of flash memory. It is also unrelated to the form factor, which is why NVMe drives can come in both M.2 or PCIe card form factors. With both form factors, the component is connecting electrically to the PC via PCIe rather than SATA.
Are all M.2 drives NVMe?
No. Remember, M.2 is just the form factor. M.2 drives can come in SATA versions (like the Crucial MX500 M.2 for example) and NVMe versions (like the Samsung 970 Pro/EVO), which describes the bus they use to electrically communicate with the other PC components. SATA M.2 SSD drives and 2.5” SATA SSDs actually operate at virtually identical spec. NVMe M.2’s on the other hand, definitely do not.
How does NVMe speed compare to SATA?
Modern motherboards use SATA III which maxes out at a throughput of 600MB/s (or 300MB/s for SATA II, in which case, it’s time to upgrade). Via that connection, most SSDs will provide Read/Write speeds in the neighborhood of 530/500 MB/s. For comparison, a 7200 RPM SATA drive manages around 100MB/s depending on age, condition, and level of fragmentation. NVMe drives, on the other hand, provide write speeds as high as 3500MB/s for Gen 3 and 5000MB/s for Gen 4. That’s 7x over SATA SSDs and as much as 35x over spinning HDDs!
So which option is best for you? Well, given the speed benefits of the NVMe drives, they’re definitely worth a look, especially if your application is hard drive intensive or requires constant hard drive reads/writes.