Pattern-based Write Scheduling and Read Balance-oriented Wear-Leveling for Solid State Drivers

This paper proposes a pattern-based I/O scheduling mechanism, which identifies frequently written data with patterns and dispatches them to the same SSD blocks having a small erase count. The data on the same block are mostly like to be invalided together, so that the overhead of garbage collection can be greatly reduced. Moreover, a read balance-oriented wear-leveling scheme is introduced to extend the lifetime of SSDs. Specifically, it distributes the hot read data in the blocks with a small erase count, to heavily erased blocks in different chips of the same SSD channel, while carrying out wear-leveling. As a result, internal parallelism at the chip level of SSD can be fully exploited for achieving better read data throughput. We conduct a series of simulation tests with a number of disk traces of real-world applications under the SSDsim platform. The experimental results show that the newly proposed mechanism can reduce garbage collection overhead by 11.3%, and the read response time by 12.8% in average, comparing to existing approaches of scheduling and wear-leveling for SSDs.