一句话：利用应用提示放宽高密度 3D NAND SSD 的读延迟约束，减少读干扰导致的后台重写，从而延长寿命。
3D NAND 通过堆叠更多单元层提升 SSD 密度，但也放大了读干扰，导致后台重写并缩短寿命。作者对 8 款先进 SSD 的寿命影响刻画显示，3D TLC/QLC SSD 可能在保修期内仅因只读负载而磨损；对另外 2 款无后台重写机制的 SSD 的读延迟刻画则表明，数据被读取越多，多数读延迟越高。基于这两项观察，论文提出放宽高密度 3D SSD 的短读延迟约束：由应用向 SSD 传递提示信息，说明期望的读性能，从而减少读引发的写入对寿命的消耗。在文件服务器应用上的实验表明，该方案可将重写导致的生命周期消耗降低最多 56%，而性能仅下降 2%。
The adoption of 3D NAND has significantly increased the SSD density; however, 3D NAND density-increasing techniques, such as extensive stacking of cell layers, can amplify read disturbances and shorten SSD lifetime. From our lifetime-impact characterization on 8 state-of-the-art SSDs, we observe that the 3D TLC/QLC SSDs can be worn-out by low read-only workloads within their warranty period since a huge amount of read disturbance-induced rewrites are performed in the background. To understand alternative read disturbance mitigation opportunities, we also conducted read-latency characterizations on 2 other SSDs without the background rewrite mechanism. The collected results indicate that, without the background rewriting, the read latencies of the majority of data become higher, as the number of reads on the data increases. Motivated by these two characterizations, in this paper, we propose to relax the short read latency constraint on the high-density 3D SSDs. Specifically, our proposal relies on the hint information passed from applications to SSDs that specifies the expected read performance. By doing so, the lifetime consumption caused by the read-induced writes can be reduced, thereby prolonging the SSD lifetime. The detailed experimental evaluations show that our proposal can reduce up to 56% of the rewrite-induced spent-lifetime with only 2% lower performance, under a file-server application.
DOI 原文 ·
@inproceedings{paperbot6113,
title = {Prolonging 3D NAND SSD lifetime via read latency relaxation},
author = {Chun-Yi Liu and Yunju Lee and Myoungsoo Jung and Mahmut Taylan Kandemir and Wonil Choi},
booktitle = {ASPLOS},
year = {2021},
doi = {10.1145/3445814.3446733}
}