RAID-Aware SSD: Improving the Write Performance and Lifespan of SSD in SSD-Based RAID-5 System

摘要

Flash memory-based SSD RAID has an excellent I/O performance with high stability, which making it get more and more attention from companies and manufacturers, especially in I/O-intensive environments. However, frequently updating parity also makes the SSD have a higher overhead in the process of garbage collection. To this end, we propose RAID-Aware SSD (RA-SSD) that could distinguish user data from parity by detecting the different access patterns from the upper RAID layer, and store them separately at different flash blocks. RA-SSD could effectively reduce the overhead of garbage collection. Simulation results show that, being deployed in a RAID-5 System, RA-SSD could reduce the number of pages copied in the process of garbage collection by up to 10%. As the overhead of garbage collection decreases, the write performance and lifespan will be improved. The extra space consumed by RA-SSD is very small, it is only about 1/10000 of the capacity of the device. Moreover, the processing logic of RA-SSD is so simple that it has very little impact on read performance.