What is NVMe technology?

In this article:

  1. Comparing Transfer Speeds: SATA vs PCIe
  2. Comparing AHCI Communication Drivers with NVMe Communication Drivers
  3. What SSD Form Factors Are Available for SATA & PCIe Data Buses?
  4. Benefits of NVMe Technology

NVMe SSDs are the latest adaptation to industrial computing.  NVMe stands for Non-Volatile Memory Express and is the new communication interface and driver that defines a command set and feature set for PCIe-based SSDs with the goal of increased performance and interoperability on a broad range of industrial systems.

Comparing Transfer Speeds: SATA vs PCIe

PCIe data buses provide a significant increase in data transfer speeds vs the SATA data bus. Using 16 lanes, PCIe Gen 4 can transfer data at 32,000 MB/s.

Data Bus Generation Transfer Speeds
SATA SATA I 150 MB/s
SATA II 300 MB/s
SATA III 600 MB/s
PCIe PCIe Gen 2 500 MB/s Per Lane
PCIe Gen 3 1,000 MB/s Per Lane
PCIe Gen 4 2,000 MB/s per Lane

Comparing AHCI Communication Drivers with NVMe Communication Drivers

AHCI NVMe
Designed for hard drives with spinning disk technology Designed for SSDs with flash technology
Has only 1 command queue Has 64,000 comman queues
Can only send 32 commands per queue Can send 64,000 commands per queue
Commands utilize high CPU cycles Commands utilise low CPU cycles
Has a latency of 6 microseconds Has a latency of 2.8 microseconds
Must communicate with the SATA controller Communicates directly with the system CPU
IOPS up to 100,000 IOPs over 1,000,000

 

What SSD Form Factors Are Available for SATA & PCIe Data Buses?

SSDs are available in a range of form factors utilising the SATA or PCIe data bus. Industrial Mini PCs are beginning to adopt M.2 storage with either the SATA or PCIe data bus. Available in three dimensions, an M.2 SSDs size can be deduced from the cards name – 2242, 2260, and 2280. The first two digits represent the M.2 cards width in mm, the latter two digits represent the M.2 cards length in mm.

The longer the M.2 SSD cards have more storage capacity due to the ability to host more NAND flash chips.

When choosing the correct length M.2 SSD you must first consider how many SSDs are to be installed into the industrial computer and how this will affect thermal management, as this is a significant factor for sustaining performance. Instability and reduced life are a side-effect if the industrial computer cannot effectively dissipate the additional heat.

Data Bus SSD Form Factor
SATA 2.5” SSD
mSATA SSD
M.2 SSD
PCIe HHHL SSD – Half Height, Half Length *
M.2 SSD
U.2 SSD

 

*AHCI versions of these drives plug into the PCIe slot but use the AHCI drivers. Some older versions of HHHL use proprietary drivers. NVMs versions typically use native OS drivers.

Benefits of NVMe Technology

  1. Superior Storage - PCIe sockets transfer up 25x more data than their SATA equivalent
  2. Superior Speed – NVMe begins sending commands more than 2x faster than AHCI drivers. NVMe Input/Output operations per second exceeds 1 million and is up to 900% faster than its AHCI equivalent.
  3. Superior Compatibility – NVMe cuts out the middleman by communicating directly with the system CPU. NVMe-based drives work with all major operating systems, regardless of form factor.
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