DPLFS: A Dual-Mode PCM-based Log-Structured File System

Dual-mode phase change memory (PCM) allows each PCM cell to operate concurrently in two modes: multi-level cell (MLC) and single-level cell (SLC), each with its own distinct features in transfer speeds and power consumption. This paper describes the design and implementation of a log-structured file system, called DPLFS, which is proposed to provide a storage system with high throughput and low latencies. DPLFS achieves this merit by exploiting the dual-mode PCM. In particular, file data in DPLFS is stored in MLC, while its metadata is maintained in SLC, and will be written back to MLC when the space in SLC is not enough. DPLFS adapts log-structured file system techniques to exploit fast random accesses in SLC and large capacity in MLC and maintains a file directory in SLC to speed up the data retrieval speed. Our experimental results show a 21% in write-intensive workloads and a 11% in read-intensive workloads, compared to the state-of-the-art file systems.