Universal Flash Storage, known as UFS, is the flash storage standard that is used in flagship phones and upper mid-range phones. The Samsung Galaxy S6 was the first phone to use UFS storage in 2015. In the years since, it has slowly been spreading to lower-cost segments of the market, to the point where the newest lower mid-range phones now also have UFS storage. UFS storage is much faster than the eMMC flash storage standard, which is still used in budget phones. In 2019, the JEDEC Solid State Technology Association, which is responsible for the development of standards for the microelectronics industry, announced UFS 3.0. While most 2019 flagships opted to stick with the older UFS 2.1 NAND, some phones such as the OnePlus 7 series, the Samsung Galaxy Fold, the Samsung Galaxy Note 10 series, and the Realme X2 Pro did opt to use the newer, faster UFS 3.0. Now, JEDEC has announced UFS 3.1, improving the UFS 3.0 standard with speed and power efficiency improvements.
The publication of UFS 3.1, JESD220E, was announced with a new optional new companion standard, JESD220-3: UFS Host Performance Booster (HPB) Extension. Both JESD220E and JESD220-3 are available for download from the JEDEC website.
The UFS 3.1 JESD220E standard brings three key improvements over UFS 3.0. First of all, it has a Write Booster, a SLC non-volatile cache that amplifies write speed. Secondly, new UFS device low power state called DeepSleep targets lower cost systems that share UFS voltage regulators with other functions. Finally, it has a Performance Throttling Notification that allows the UFS device to notify the host when storage performance is throttled to high temperature. The use of an SLC non-volatile cache is probably most crucial feature here, as it will help improve real-world performance. This technology is used in devices that use mobile NVMe SSDs, such as the Apple iPhone and iPad. Also, all of these features are already supported by SSDs, so the inclusion of these features in UFS 3.1 will help close the gap between the two.
The JESD220-3 Host Performance Booster (HPB) Extension) provides an option to cache the UFS device logical-to-physical address map in the system’s DRAM. JEDEC states: “For UFS devices with a large density, using system DRAM provides larger and faster caching thereby improving the read performance of the device”.
JEDEC UFS has continued its collaboration with the MIPI Alliance to form its Interconnect Layer. It references the MIPI M-PHY v4.1 physical layer specification and the MIPI UniPro v1.8 transport layer specification.
Now that UFS 3.1 has been announced, it’s probable that it will be adopted by some 2020 flagships. The OnePlus 8 series would be a prime contender, and so would the Samsung Galaxy Note 20 series. It’s not as big an update as UFS 3.0 was over UFS 2.1 (as the theoretical top bandwidth speed remains the same at 23.2Gbps), but the real-world improvements in storage performance and battery life for lower cost devices will be welcome. Storage performance has historically been a bottle-neck on mobile devices, so it’s good to see continuing improvements here.
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