Exploiting request characteristics and internal parallelism to improve SSD performance

In this paper, we propose a new I/O scheduler for SSDs, called Amphibian, which exploits the up-level request characteristics and the low-level internal parallelism of flash chips to improve the performance of SSD-based storage systems. Amphibian includes two parts: the size-based request ordering that gives higher priority to first processing the small requests and the Garbage Collection (GC) aware request dispatching that avoids issuing requests to the flash chips that are in the GC state. By first processing the small requests and avoiding issuing the GC-conflict requests in the I/O waiting queue, the average waiting times of the requests are reduced significantly. The extensive evaluation results show that compared with existing I/O schedulers, Amphibian improves the throughput and the average response times significantly. Consequently, the I/O performance of the SSD-based storage systems is improved.