R&D: Is Garbage Collection Overhead Gone? Case study of F2FS on ZNS SSDs

ACM Digital Library has published, in HotStorage ’23: Proceedings of the 15th ACM Workshop on Hot Topics in Storage and File Systems, an article written by Dongjoo Seo, Ping-Xiang Chen, University of California, Irvine, CA, USA, Huaicheng Li, Virginia Tech, Blacksburg, USA, Matias Bjørling, Western Digital, Copenhagen, Denmark, and Nikil Dutt, University of California, Irvine, CA, USA.

Abstract: “The sequential write nature of ZNS SSDs makes them very well-suited for log-structured file systems. The Flash-Friendly File System (F2FS), is one such log-structured file system and has recently gained support for use with ZNS SSDs. The large F2FS over-provisioning space for ZNS SSDs greatly reduces the garbage collection (GC) overhead in the log-structured file systems. Motivated by this observation, we explore the trade-off between disk utilization and over-provisioning space, which affects the garbage collection process, as well as the user application performance. To address the performance degradation in write-intensive workloads caused by GC overhead, we propose a modified free segment-finding policy and a Parallel Garbage Collection (P-GC) scheme for F2FS that efficiently reduces GC overhead. Our evaluation results demonstrate that our P-GC scheme can achieve up to 42% performance enhancement with various workloads.“