# Universal Flash Storage

Universal Flash Storage (UFS) is a flash storage specification for digital cameras, mobile phones and consumer electronic devices. It was designed to bring higher data transfer speed and increased reliability to flash memory storage, while reducing market confusion and removing the need for different adapters for different types of cards. The standard encompasses both packages permanently embedded (via ball grid array package) within a device (eUFS), and removable UFS memory cards.

## Overview

UFS uses NAND flash. It may use multiple stacked 3D TLC NAND flash dies (integrated circuits) with an integrated controller.
The proposed flash memory specification is supported by consumer electronics companies such as Nokia, Sony Ericsson, Texas Instruments, STMicroelectronics, Samsung, Micron, and SK Hynix. UFS is positioned as a replacement for eMMCs and SD cards. The electrical interface for UFS uses the M-PHY, developed by the MIPI Alliance, a high-speed serial interface targeting 2.9 Gbit/s per lane with up-scalability to 5.8 Gbit/s per lane. UFS implements a full-duplex serial LVDS interface that scales better to higher bandwidths than the 8-lane parallel and half-duplex interface of eMMCs. Unlike eMMC, Universal Flash Storage is based on the SCSI architectural model and supports SCSI Tagged Command Queuing. The standard is developed by, and available from, the JEDEC Solid State Technology Association.

### Software support

The Linux kernel supports UFS. OpenBSD 7.3 and later support UFS. Windows 10 and later support UFS.

## History

In 2010, the Universal Flash Storage Association (UFSA) was founded as an open trade association to promote the UFS standard.
In September 2013, JEDEC published JESD220B UFS 2.0 (update to UFS v1.1 standard published in June 2012). JESD220B Universal Flash Storage v2.0 offers increased link bandwidth for performance improvement, a security features extension and additional power saving features over the UFS v1.1.
On 30 January 2018 JEDEC published version 3.0 of the UFS standard, with a higher 11.6 Gbit/s data rate per lane (1450 MB/s) with the use of MIPI M-PHY v4.1 and UniProSM v1.8. At the MWC 2018, Samsung unveiled embedded UFS (eUFS) v3.0 and uMCP (UFS-based multi-chip package) solutions.
On 30 January 2020 JEDEC published version 3.1 of the UFS standard. UFS 3.1 introduces Write Booster, Deep Sleep, Performance Throttling Notification and Host Performance Booster for faster, more power efficient and cheaper UFS solutions. The Host Performance Booster feature is optional. Before the UFS 3.1 standard, the SLC cache feature is optional on UFS device, which is a de facto feature on personal SSDs.
In 2022 Samsung announced version 4.0 doubling from 11.6 Gbit/s to 23.2 Gbit/s with the use of MIPI M-PHY v5.0 and UniPro v2.0. UFS 4.0 introduces File Based Optimization.
As of Q2 2024, Zoned UFS (ZUFS) is in development by SK hynix.

## Notable devices

In February 2013, semiconductor company Toshiba Memory (now Kioxia) started shipping samples of a 64 GB NAND flash chip, the first chip to support the then new UFS standard.
In April 2015, Samsung's Galaxy S6 family was the first phone to ship with eUFS storage using the UFS 2.0 standard.
On 7 July 2016, Samsung announced its first UFS cards, in 32, 64, 128, and 256 GB storage capacities. The cards were based on the UFS 1.0 Card Extension Standard. The 256 GB version was reported to offer sequential read performance up to 530 MB/s and sequential write performance up to 170 MB/s and random performance of 40,000 read IOPS and 35,000 write IOPS. However, they were apparently not actually released to the public.
On 17 November 2016, Qualcomm announced the Snapdragon 835 SoC with support for UFS 2.1.
On 14 May 2019, OnePlus introduced the OnePlus 7 and OnePlus 7 Pro, the first phones to feature built-in eUFS 3.0 (The Galaxy Fold, originally planned to be the first smartphone to feature UFS 3.0 was ultimately delayed after the OnePlus 7's launch).
The first UFS cards began to be publicly sold in early 2020. According to a Universal Flash Storage Association press release, Samsung planned to transition its products to UFS cards during 2020. Several consumer devices with UFS card slots have been released in 2020.
On 08 December 2022, IQOO announced the IQOO 11 which was the first phone to release with UFS 4.0. After that, other Android OEMs started using this storage solution on their flagship to upper mid-range category smartphones.

## Version comparison
### UFS

| Version | Introduced | Bandwidth per lane | Maximum lanes | Maximum bandwidth | M-PHY version | UniPro version |
| 1.0 | 2011-02-24 | 300 MB/s | 1 | 300 MB/s | 1.0 | 1.4 |
| 1.1 | 2012-06-25 | 300 MB/s | 1 | 300 MB/s | 1.0 | 1.4 |
| 2.0 | 2013-09-18 | 600 MB/s | 2 | 1200 MB/s | 3.0 | 1.6 |
| 2.1 | 2016-04-04 | 600 MB/s | 2 | 1200 MB/s | 3.0 | 1.6 |
| 2.2 | 2020-08 | 600 MB/s | 2 | 1200 MB/s | ? | ? |
| 3.0 | 2018-01-30 | 1450 MB/s | 2 | 2900 MB/s | 4.1 | 1.8 |
| 3.1 | 2020-01-30 | 1450 MB/s | 2 | 2900 MB/s | 4.1 | 1.8 |
| 4.0 | 2022-08-17 | 2900 MB/s | 2 | 5800 MB/s | 5.0 | 2.0 |
| 4.1 | 2025-01-08 | 2900 MB/s | 2 | 5800 MB/s | 5.0 | 2.0 |

### UFS Card

| Version | Introduced | Bandwidth per lane | Maximum lanes | Maximum bandwidth | M-PHY version | UniPro version |
| 1.0 | 2016-03-30 | 600 MB/s | 1 | 600 MB/s | 3.0 | 1.6 |
| 1.1 | 2018-01-30 | 600 MB/s | 1 | 600 MB/s | 3.0 | 1.6 |
| 3.0 | 2020-12-08 | 1200 MB/s | 1 | 1200 MB/s | 4.1 | 1.8 |

## Implementation

* UFS 2.0 has been implemented in Snapdragon 820 and 821. Kirin 950 and 955. Exynos 7420. NVIDIA Jetson AGX Xavier SOMs
* UFS 2.1 has been implemented in Snapdragon 712 (710&720G), 730G, 732G, 835, 845 and 855. Kirin 960, 970 and 980. Exynos 9609, 9610, 9611, 9810 and 980.
* UFS 3.0 has been implemented in Snapdragon 855, 855+, 860, 865, Exynos 9820–9825, and Kirin 990.
* UFS 3.1 has been implemented in Snapdragon 855+/860, Snapdragon 865, Snapdragon 870, Snapdragon 888, Exynos 2100, and Exynos 2200.
* UFS 4.0 has been implemented in MediaTek Dimensity 9200, MediaTek Dimensity 8300 and Snapdragon 8 Gen 2.

## Complementary UFS standards

On 30 March 2016, JEDEC published version 1.0 of the UFS Card Extension Standard (JESD220-2), which offered many of the features and much of the same functionality as the existing UFS 2.0 embedded device standard, but with additions and modifications for removable cards.
Also in March 2016, JEDEC published version 1.1 of the UFS Unified Memory Extension (JESD220-1A), version 2.1 of the UFS Host Controller Interface (UFSHCI) standard (JESD223C), and version 1.1A of the UFSHCI Unified Memory Extension standard (JESD223-1A).
On January 30, 2018, the UFS Card Extension standard was updated to version 1.1 (JESD220-2A), and the UFSHCI standard was updated to version 3.0 (JESD223D), to align with UFS version 3.0.

## Rewrite cycle life

A UFS drive's rewrite life cycle affects its lifespan. There is a limit to how many write/erase cycles a flash block can accept before it produces errors or fails altogether. Each write/erase cycle causes a flash memory cell's oxide layer to deteriorate. The reliability of a drive is based on three factors: the age of the drive, total terabytes written over time and drive writes per day. This is typical of flash memory in general.