An on-line hot data identification for flash-based storage using sampling mechanism
ACM SIGAPP Applied Computing Review
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Areal density scaling in magnetic hard drives isin jeopardy as magnetic particles become unstable when they are sufficiently small. Shingled recording holds great promise to mitigate the problem of density scaling cost-effectively by overlapping data tracks. However, this innovative technology suffers severely from slow small writes. This prevents shingle recording from being widely adapted in practice. This paper presents a new hybrid storage architecture that combines a shingled-recording magnetic disk and a fast SSD cache to achieve a high-capacity storage system without any compromise to performance. We propose a new wave-like shingled recording that overlaps adjacent tracks from two opposite radial directions. This new schemes doubles the areal density of conventional circular log-based shingled recording. We also design a new replacement strategy to manage the hybrid system to effectively eliminate the performance degradation. We evaluate our design based on a prototype implementation. Experimental results under 12 I/O workloads show that our hybrid system exhibits a sustained performance comparable to a disk with no shingled-recording.