@article{Liu2019, 
author = {Wen-Guo Liu and Ling-Fang Zeng and Dan Feng and Kenneth B. Kent},
title = {ROCO: Using a Solid State Drive Cache to Improve the Performance of a Host-Aware Shingled Magnetic Recording Drive},
year = {2019},
journal = {Journal of Computer Science and Technology},
volume = {34},
number = {1},
pages = {61-76},
keywords = {solid state drive (SSD) cache, host-aware shingled magnetic recording (HA-SMR) drive, zone-oriented block reordering, zone-oriented hot/cold data identification, data replacement algorithm},
url = {https://www.sciopen.com/article/10.1007/s11390-019-1899-7},
doi = {10.1007/s11390-019-1899-7},
abstract = {Shingled magnetic recording (SMR) can effectively increase the capacity of hard disk drives (HDDs). Hostaware SMR (HA-SMR) is expected to be more popular than other SMR models because of its backward compatibility and new SMR-specific APIs. However, an HA-SMR drive often suffers performance degradation under write-intensive workloads because of frequent non-sequential writes buffered in the disk cache. The non-sequential writes mainly come from update writes, small random writes and out-of-order writes. In this paper, we propose a hybrid storage system called ROCO which aims to use a solid state drive (SSD) cache to improve the performance of an HA-SMR drive. ROCO reorders out-of-order writes belonging to the same zone and uses the SSD cache to absorb update writes and small random writes. We also design a data replacement algorithm called CREA for the SSD cache. CREA first conducts zone-oriented hot/cold data identification to identify cold-cached zones and hot-cached zones, and then evicts data blocks belonging to colder zones with higher priorities that can be sequentially written or written through host-side read-modify-write operations. It gives the lowest priority to data blocks belonging to the hottest-cached zone that have to be non-sequentially written. Experimental results show that ROCO can effectively reduce non-sequential writes to the HA-SMR drive and improve the performance of the HA-SMR drive.}
}