UFS Surpasses Emmc in Mobile Storage Tech Race

In the world of high-performance mobile devices, storage speed is like the horsepower of a racing engine, directly determining the smoothness of user experience. For years, eMMC (embedded Multi-Media Controller) was the mainstream choice for data storage in smartphones and tablets. However, as application scenarios become increasingly complex and data volumes explode, a more advanced storage technology – UFS (Universal Flash Storage) – has emerged as the future storage standard. The 2020 release of UFS 3.1 in particular has pushed mobile storage performance to new heights. But what exactly is UFS 3.1? How does it compare to eMMC? This article provides an in-depth analysis of their differences and explores future trends in mobile storage technology.

UFS, or Universal Flash Storage, is a flash storage specification designed for digital cameras, mobile phones, consumer electronics, automotive, and industrial automation equipment. Its core concept focuses on providing high-speed data transfer, high reliability, and low-power flash memory solutions. The UFS standard is developed and managed by JEDEC Solid State Technology Association.

Inspired by the high performance of SATA interfaces commonly used in PCs while maintaining eMMC's low-power advantages, UFS aims to combine the best of both worlds. Unlike previous eMMC standards, UFS is based on the SCSI architecture model and supports SCSI Tagged Command Queuing (TCQ), allowing operating systems to send multiple read/write requests to storage devices. This parallel processing capability significantly improves storage efficiency.

The UFS standard seeks to achieve the perfect combination of maximum performance and highest quality, delivering superior overall user experience. This next-generation flash technology provides faster response times for data input/output, accelerating file transfers, boot speeds, and data copying.

As a result, UFS enables seamless multitasking – users can simultaneously watch high-quality videos, play bandwidth-intensive games, and run multiple background processes without interruption. This capability is equally crucial for automotive applications where increasing numbers of cameras and sensors are making storage bandwidth a limiting factor.

The UFS 3.1 standard offers significant performance improvements over eMMC (embedded Multi-Media Card) storage. Below is a detailed comparative analysis across multiple dimensions:

UFS utilizes a serial LVDS (Low-Voltage Differential Signaling) interface with independent read/write paths, enabling true full-duplex communication where read and write operations can occur simultaneously. In contrast, eMMC employs a half-duplex interface that can only perform either reading or writing at any given moment.

Advantages of Full-Duplex:

Full-duplex communication allows simultaneous two-way data transmission, similar to a two-way street where traffic flows in both directions concurrently. This dramatically improves data transfer efficiency and reduces wait times. For mobile devices, it means faster app loading, quicker file transfers, and smoother user experience.

Limitations of Half-Duplex:

Half-duplex communication resembles a one-way street where traffic must alternate directions. This creates data transfer bottlenecks that degrade overall performance.

UFS features Command Queuing (CQ) that effectively sequences all operations and commands for execution. This enables simultaneous processing of multiple commands with real-time adjustment of task order and priority, significantly boosting storage efficiency.

eMMC lacks command queuing, forcing it to complete one process before starting the next. This serial processing approach limits performance, especially when handling numerous concurrent requests.

How Command Queuing Works:

Command queuing acts like an intelligent dispatcher, receiving multiple read/write requests from the operating system and scheduling them based on priority and resource availability. By optimizing execution order, it minimizes latency and maximizes storage efficiency.

Bottlenecks Without Command Queuing:

Without command queuing, eMMC must execute requests sequentially as received. Even if later requests have higher priority or could complete faster, they must wait for prior requests to finish, creating unnecessary delays.

UFS holds an overwhelming speed advantage over eMMC. UFS 3.1 offers theoretical maximum bandwidth of 23.2 Gbps (2.9 GB/s), while eMMC 5.1 maxes out at 400 MB/s – making UFS 3.1 over 7 times faster.

Real-World Speed Differences:

This translates to faster app launches, quicker file transfers, reduced game loading times, and overall snappier system responsiveness in actual usage.

User Experience Improvements:

Faster storage enables quicker data access and processing, boosting both productivity and entertainment. Users benefit from speedier opening of large files, faster photo/video transfers, quicker app launches, and smoother gaming experiences.

Despite its performance superiority, UFS incorporates optimized power management to minimize energy consumption while maintaining high performance – crucial for extending mobile device battery life.

UFS's Power-Saving Technologies:

UFS employs multiple low-power techniques including low-voltage operation, dynamic frequency adjustment, and power gating that adjust consumption based on actual workload.

eMMC's Power Challenges:

While eMMC has some power advantages, its consumption typically exceeds UFS in high-performance applications as it requires higher voltage and more frequent access to achieve comparable performance.

Given its superior performance and efficiency, UFS dominates premium smartphones, tablets, and gaming devices, while eMMC remains prevalent in mid-to-low-end devices and embedded systems.

UFS's Future Applications:

With 5G, AI, and IoT advancements driving ever-higher storage demands, UFS's high-performance, low-power solution will play an increasingly vital role in future mobile and embedded systems.

eMMC's Niche:

While UFS dominates the premium segment, eMMC maintains relevance in cost-sensitive applications where extreme performance isn't required.

UFS continues evolving toward higher speeds, lower power consumption, greater reliability, and smarter functionality. Key development trends include:

• Higher Speeds: Future UFS will adopt advanced interface and storage cell technologies for faster data transfer. UFS 4.0 already implements MIPI M-PHY v5.0 interface with theoretical maximum bandwidth of 23.2 Gbps (2.9 GB/s).
• Lower Power Consumption: Advanced power management will further reduce energy use and extend battery life.
• Enhanced Reliability: Improved error correction and data protection technologies will prevent data loss.
• Smarter Storage: Future UFS will integrate intelligent features like data compression, encryption, and management to improve efficiency and security.

UFS outperforms eMMC across all critical metrics – interface design, command processing, speed, power efficiency, and application scenarios. As mobile devices demand ever-higher storage performance, UFS will inevitably replace eMMC as the future standard. While eMMC retains cost advantages for now, UFS's maturing technology and declining prices will gradually erode even this niche. For consumers prioritizing peak performance and exceptional user experience, devices equipped with UFS storage represent the clear choice.