Abstract-Shingled Magnetic Recording technology is expected to play a major role in the next generation of hard disk drives. But it introduces some unique challenges to system software researchers and prototype hardware is not readily available for the broader research community. It is crucial to work on system software in parallel to hardware manufacturing, to ensure successful and effective adoption of this technology.In this work, we present a novel Shingled Write Disk (SWD) emulator that uses a hard disk utilizing traditional Perpendicular Magnetic Recording (PMR) and emulates a Shingled Write Disk on top of it. We implemented the emulator as a pseudo block device driver and evaluated the performance overhead incurred by employing the emulator. The emulator has a slight overhead which is only measurable during pure sequential reads and writes. The moment disk head movement comes into picture, due to any random access, the emulator overhead becomes so insignificant as to become immeasurable.
Abstract-Shingled Magnetic Recording (SMR) is a means of increasing the density of hard drives that brings a new set of challenges. Due to the nature of SMR disks, updating in place is not an option. Holes left by invalidated data can only be filled if the entire band is reclaimed, and a poor band compaction algorithm could result in spending a lot of time moving blocks over the lifetime of the device. We propose using write frequency to separate blocks to reduce data movement and develop a band compaction algorithm that implements this heuristic. We demonstrate how our algorithm results in improved data management, resulting in an up to 47% reduction in required data movements when compared to naive approaches to band management.
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