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 ne...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.展开更多
基金the National Natural Science Foundation of China under Grant No.61472153.
文摘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.
