Out-of-channel data placement for balancing wear-out and I/O workloads in RAID-enabled SSDs

Channel-level RAID implementation SSDs can fight against channel failures inside SSDs, but greatly suffer from imbalanced wear-out (i.e. erase) and I/O workloads across all SSD channels, due to the nature of in-channel updates on data/parity chunks of data stripes. This paper proposes exchanging channel locations of data/parity chunks belonging to the same stripe when satisfying update (write) requests, termed as out-of-channel data placement. Consequently, it can smooth wear-out and I/O workloads across SSD channels, thus reducing I/O response time. Through a series of emulation experiments on several realistic disk traces, we show that our proposal can greatly improve I/O performance, as well as noticeably balance the wear-out and I/O workloads, in contrast to related methods.