Move-On-Modify: An Efficient yet Crash-Consistent Update Strategy for Interlaced Magnetic Recording

Emerging Interlaced Magnetic Recording (IMR) technology delivers higher areal density for hard drives by interlacing tracks. However, to update the interlaced tracks overlapped by valid data, IMR must entail extra I/Os to rewrite tracks, and the typical read-modify-write (RMW) update strategy further amplifies extra I/Os and deteriorates write performance for ensuring crash consistency. In contrast to the state-of-the-art designs that focus on reducing the occurrence of RMW(s), this paper presents a novel efficient-yet-crash-consistent update strategy, namely move-on-modify (MOM), to completely substitute the typical RMW. By moving data upon updating tracks, MOM essentially circumvents the redundant data restorations of RMW with the ensured crash consistency, and simultaneously takes advantage of these data movements to properly migrate data for reducing the probability of incurring track rewrites without taking extra data migrations. Evaluation results show that MOM not only effectively boosts write performance by at least 77.89% via minimizing extra I/Os, but also greatly benefits the state-of-the-art designs.