Most drives currently use the AHCI (Advanced Host Controller Interface), which dates back to 2004. AHCI was originally designed for high latency rotating media and can't take full advantage of SSDs. Advancements in non-volatile storage such as NAND and MRAM have led the industry to develop a better software interface to abolish the limits of AHCI.
AnandTech describes the new interface: "The result is NVMe, short for Non-Volatile Memory Express. It was developed by an industry consortium with over 80 members and the development was directed by giants like Intel, Samsung, and LSI. NVMe is built specifically for SSDs and PCIe and as software interfaces usually live for at least a decade before being replaced, NVMe was designed to be capable of meeting the industry needs as we move to future memory technologies (i.e. we'll likely see RRAM and MRAM enter the storage market before 2020)."
The biggest advantage of NVMe is its low latency of 2.8 µs compared to 6.0 µs for AHCI. Thanks to the lower latency, disk usage time will decrease, your computer will spend more time at idle, and thus your battery life will be increased. In addition, there could be some situations where NVMe's better queue support helps with performance.
NVMe is designed to meet the industry's needs as we move to future memory technologies. Apple's first device to support the technology is the new 12-inch Retina MacBook. It's likely that future Apple devices will take advantage of NVMe's performance as well.
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