P3Stor: A parallel, durable flash-based SSD for enterprise-scale storage systems

Abstract

Driven by data-intensive applications, flash-based solid state drives (SSDs) have become increasingly popular in enterprise-scale storage systems. Flash memory exhibits inherent parallelism. However, existing solid state drives have not fully exploited this superiority. We propose P3Stor, a parallel solid state storage architecture that makes full use of flash memory by utilizing module- and bus-level parallelisms to increase average bandwidth and employing chip-level interleaving to hide I/O latency. To improve the bandwidth utilization of traditional interface protocols (e.g., SATA), P3Stor adopts PCI-E interface to support concurrent transactions. Based on the proposed parallel architecture, we design a lazy flash translation layer (LazyFTL) to manage the address space. The proposed LazyFTL adopts flexible super page-level mapping scheme to support multi-level parallelisms. It is able to distinguish hot data from cold data, and hot data identification enables LazyFTL to direct hot and cold data to separate physical blocks, which reduces page migrations when reclaiming blocks. As garbage collector migrates fewer valid pages, write amplification is significantly reduced, which in turn helps to extend the life span. Moreover, LazyFTL rarely triggers wear-leveling process. The lazy wear-leveling mechanism protects users’ requests from being disrupted by background operations. With the guidance of hot data identification, an intelligent write buffer is used to reduce program operations to flash chips. This is meaningful in extending P3Stor’s life span. The performance evaluation using trace-driven simulations and theoretical analysis shows that P3Stor achieves high performance and its life span is more than doubled.