Enhancing SSD Reliability through Efficient RAID Support

Abstract

A serious problem with current SSDs is its low reliability due to their primary component, flash-memory, that has high error rate and limited erase count. Adopting RAID architecture is a reasonable way to increase reliability of SSDs. In this paper, we propose Dynamic and Variable Size Striping-RAID (DVS-RAID) that dynamically constructs a variable size stripe based on arrival order of write requests such that write requests are sequentially written to a stripe improving the performance and lifetime of SSDs. To increase the reliability of small writes without making use of non-volatile RAM, DVS-RAID employs variable size striping, which constructs a new stripe with data written to portions of a full stripe and writes a parity for that partial stripe. We implement DVS-RAID in the DiskSim SSD extension, and experimental results based on trace-driven simulations show that DVS-RAID out-performs the conventional RAID-5 scheme in terms of performance and lifetime of SSDs.