CNEX: LightNVM: The Open Channel SSD Subsystem
Channel: Open Compute Project
Date: 14/03/2017

Speaker: Matias Bjorling

As Solid-State Drives (SSDs) become commonplace in data-centers and storage arrays, there is a growing demand for predictable latency. Traditional SSDs, serving block I/Os, fail to meet this demand. They offer a high-level of abstraction at the cost of unpredictable performance and suboptimal resource utilization. We propose that SSD management trade-offs should be handled through Open-Channel SSDs, a new class of SSDs, that give hosts control over their internals. We present our experience building LightNVM, the Open-Channel SSD subsystem. We introduce a new Physical Page Address I/O interface that exposes SSD parallelism and storage media characteristics. LightNVM integrates into traditional storage stacks, while also enabling storage engines to take advantage of the new I/O interface. Our experimental results demonstrate that LightNVM has modest host overhead, that it can be tuned to limit read latency variability and that it can be customized to achieve predictable I/O latencies.