SMRC: An Endurable SSD Cache for Host-Aware Shingled Magnetic Recording Drives

Host-aware shingled magnetic recording (HA-SMR) drives deliver higher disk capacity and expose internal zones to host, but their performance can be severely degraded when subjected to nonsequential writes (NSWs). Using solid state drives (SSDs) as a cache layer to proactively cache NSWs can alleviate this performance degradation. However, existing SSD caching designs are not capable of identifying and selectively caching NSWs, which incurs ineffectual SSD write traffic and excessively wears the limited write endurance of SSD. In this paper, we propose an endurable SMR-oriented SSD Caching (SMRC) framework. SMRC leverages the intrinsic host-aware property of HA-SMR drives to filter both sequential writes and innocuous NSWs out of SSD. Besides, SMRC reorganizes the cached NSWs to evict them with cleaning-friendly write traffic to HA-SMR drives. Our experimental results show that SMRC can effectively reduce SSD write traffic and improve system performance compared with existing SSD caching designs.