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ROCO: Using a Solid State Drive Cache to Improve the Performance of a Host-Aware Shingled Magnetic Recording Drive

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 degradat...

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Bibliographic Details
Published in:Journal of computer science and technology 2019, Vol.34 (1), p.61-76
Main Authors: Liu, Wen-Guo, Zeng, Ling-Fang, Feng, Dan, Kent, Kenneth B.
Format: Article
Language:English
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Summary: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.
ISSN:1000-9000
1860-4749
DOI:10.1007/s11390-019-1899-7