H-SWD: Incorporating hot data identification into shingled write disks

Shingled write disk (SWD) is a magnetic hard disk drive that adopts the shingled magnetic recording (SMR) technology to overcome the areal density limit faced in conventional hard disk drives (HDDs). The SMR design enables SWDs to achieve two to three times higher areal density than the HDDs can reach, but it also makes SWDs unable to support random writes/in-place updates with no performance penalty. In particular, a SWD needs to concern about the random write/update interference, which indicates writing to one track overwrites the data previously stored on the subsequent tracks. Some research has been proposed to serve random write/update out-of-place to alleviate the performance degradation at the cost of bringing in the concept of garbage collection. However, none of these studies investigate SWDs based on the garbage collection performance. In this paper, we propose a SWD design called Hot data identification-based Shingled Write Disk (H-SWD). The H-SWD adopts a window-based hot data identification to effectively manage data in the hot bands and the cold bands such that it can significantly reduce the garbage collection overhead while preventing the random write/update interference. The experimental results with various realistic workloads demonstrates that H-SWD outperforms the Indirection System. Specifically, incorporating a simple hot data identification empowers the H-SWD design to remarkably improve garbage collection performance.