StrataJ: Enhancing File System Journaling Scalability via Adaptive Concurrency Control and Full-Stack Optimizations

The scalability of file system journaling faces significant challenges due to the increasing concurrency demands of modern multi-core CPUs and high throughput NVMe SSDs. However, our study reveals that the concurrency of journaling should be carefully adjusted to the workload, and the underlying I/O stack must be customized to better support concurrent journaling. To address these challenges, we propose StrataJ , a full-stack journaling system designed to enhance scalability through cross-layered optimizations spanning the journaling, block I/O, and driver layers. First, we design an adaptive journaling layer that dynamically adjusts the number of journaling streams based on the real-time analysis of workloads. Second, we propose a scalable I/O control mechanism in the block layer, which eliminates contention by parallelizing writeback throttling and physical region page (PRP) management. Third, we develop a decentralized I/O virtual address (IOVA) management scheme in the driver layer, which enables different regions of the address space to flush cache independently, thus in parallel. Our evaluations show that StrataJ significantly outperforms state-of-the-art systems across varied workloads, achieving up to 3.12 ×, 1.59 × and 2.30 × speedups on FxMark, Filebench, and RocksDB, respectively.