Unleashing Zoned UFS: Cross-Layer Optimizations for Next-Generation Mobile Storage

Zoned UFS (ZUFS) has emerged as a next-generation mobile storage technology that reduces the logical-to-physical (L2P) mapping overhead of conventional UFS (CUFS) by enforcing sequential writes within fixed-size zones. While the concept appears straightforward, deploying ZUFS in commercial smartphones introduces non-trivial challenges across the mobile storage stack. In this paper, we identify three key obstacles: managing limited SRAM across multiple open zones, ensuring end-to-end write ordering guarantees, and mitigating severe garbage collection overhead caused by large zones.

We address these challenges through cross-layer optimizations spanning device firmware, the SCSI/UFS driver, the block layer, F2FS, and Android framework: a dynamic deviceside buffer management scheme that opportunistically shares SRAM, a write ordering mechanism that eliminates reordering hazards, and a proactive garbage collection framework that reclaims free space in the background. Evaluation on a commercial smartphone shows that ZUFS sustains over 2x higher write throughput under fragmentation and reduces mobile game loading time by 14% compared to CUFS, while maintaining stable read performance. These results demonstrate that ZUFS's full potential can only be realized through coordinated redesign across the entire mobile storage stack.