On the Design of SMR HDD Block Device Driver

摘要

This paper studies the design of host-managed SMR HDD. To obviate any changes to existing filesystems and applications, this paper focuses on making the host-side block device driver solely responsible for managing SMR HDD. The key is to make block device driver elastically utilize the host-side memory resource to realize address translation and mitigate SMR HDD performance degradation. Under this framework, this paper presents a set of techniques, including defragmentation-centric write buffer management, fragmentation-adaptive tree-based address mapping, and fragmentation-aware GC, which together can efficiently utilize host memory resource to realize address translation and mitigate drive performance degradation. Using a variety of disk access IO traces and benchmarks, we carried out experiments that well demonstrate the effectiveness of the proposed design techniques.