TY - GEN

T1 - Practical implication of analytical models for SSD write amplification

AU - Park, Changhyun

AU - Lee, Seongjin

AU - Won, Youjip

AU - Ahn, Soohan

N1 - Publisher Copyright:
© 2017 ACM.

PY - 2017/4/17

Y1 - 2017/4/17

N2 - A number of analytical models have been proposed to estimate the write amplification of the Flash storage to obtain the expected lifespan. This work is dedicated to examining the practical implication of the four existing analytical models for estimating the write amplification: Coupon Collector, Uniform Distribution, Expected Value and Markov model. Since the models assume uniform random workload in full utilization of an SSD to predict write amplification, they are not applicable in predicting write amplification in general workload. Moreover, the existing models have not been verified with the real SSD. In this work, we compare the write amplification of the models with that of a real SSD. When we use 0.147 as the overprovisioning factor of an SSD while running uniform random workload, the write amplification of Uniform Distribution, Expected Value, Markov model is 3.90, 4.08, and 4.08, respectively. However, write amplification of the real SSD shows 1.19, which is very different from that of the prediction models. Through experiment, we found that write amplification is closely related to the value of overprovisioning factor. To improve the accuracy of existing prediction models, we update the overprovision-ing factor to take account of the ratio of a hot file and the utilization of the storage. We also find that by setting the overprovisioning factor to 1.15, we can obtain write amplification of 1.2 which is close to the write amplification of general workload in a real SSD.

AB - A number of analytical models have been proposed to estimate the write amplification of the Flash storage to obtain the expected lifespan. This work is dedicated to examining the practical implication of the four existing analytical models for estimating the write amplification: Coupon Collector, Uniform Distribution, Expected Value and Markov model. Since the models assume uniform random workload in full utilization of an SSD to predict write amplification, they are not applicable in predicting write amplification in general workload. Moreover, the existing models have not been verified with the real SSD. In this work, we compare the write amplification of the models with that of a real SSD. When we use 0.147 as the overprovisioning factor of an SSD while running uniform random workload, the write amplification of Uniform Distribution, Expected Value, Markov model is 3.90, 4.08, and 4.08, respectively. However, write amplification of the real SSD shows 1.19, which is very different from that of the prediction models. Through experiment, we found that write amplification is closely related to the value of overprovisioning factor. To improve the accuracy of existing prediction models, we update the overprovision-ing factor to take account of the ratio of a hot file and the utilization of the storage. We also find that by setting the overprovisioning factor to 1.15, we can obtain write amplification of 1.2 which is close to the write amplification of general workload in a real SSD.

KW - Overprovisioning

KW - Solid state drive

KW - Write amplification

UR - http://www.scopus.com/inward/record.url?scp=85019051418&partnerID=8YFLogxK

U2 - 10.1145/3030207.3030219

DO - 10.1145/3030207.3030219

M3 - Conference contribution

AN - SCOPUS:85019051418

T3 - ICPE 2017 - Proceedings of the 2017 ACM/SPEC International Conference on Performance Engineering

SP - 257

EP - 262

BT - ICPE 2017 - Proceedings of the 2017 ACM/SPEC International Conference on Performance Engineering

PB - Association for Computing Machinery, Inc

T2 - 8th ACM/SPEC International Conference on Performance Engineering, ICPE 2017

Y2 - 22 April 2017 through 26 April 2017

ER -