Design of RDD Persistence Method in Spark for SSDs

SSD (solid-state drive) and HDD (hard disk drive) hybrid storage system has been widely used in big data computing datacenters. The workloads should be able to persist data of different characteristics to SSD or HDD on demand to improve the overall performance of the system. Spark is an industry-wide efficient data computing framework, especially for the applications with multiple iterations. The reason is that Spark can persist data in memory or hard disk, and persisting data to the hard disk can break the insufficient memory limits on the size of the data set. However, the current Spark implementation does not specifically provide an explicit SSD-oriented persistence interface, although data can be distributed proportionally to different storage mediums based on configuration information, and the user can not specify RDD's persistence locations according to the data characteristics, and thus the lack of relevance and flexibility. This has not only become a bottleneck to further enhance the performance of Spark, but also seriously affected the played performance of hybrid storage system. This paper presents the data persistence strategy for SSD for the first time as we know. We explore the data persistence principle in Spark, and optimize the architecture based on hybrid storage system. Finally, users can specify RDD's storage mediums explicitly and flexibly leveraging the persistence API we provided. Experimental results based on SparkBench shows that the performance can be improved by an average of 14.02%.