Prolonging 3D NAND SSD lifetime via read latency relaxation
Prolonging 3D NAND SSD lifetime via read latency relaxation
复制标题
DOI：
10.1145/3445814.3446733
复制
发表时间：
2021-04
期刊：
影响因子：
--
通讯作者：
Chun-Yi Liu;Yunju Lee;Myoungsoo Jung;M. Kandemir;Wonil Choi
中科院分区：
文献类型：
--
作者：
Chun-Yi Liu;Yunju Lee;Myoungsoo Jung;M. Kandemir;Wonil Choi
3D NAND的采用显著提高了SSD的密度；然而，3D NAND密度增加技术，如单元层的广泛堆叠，会放大读取干扰，缩短SSD寿命。从我们对8个最先进的固态硬盘的寿命影响特征中，我们观察到3D TLC/QLC固态硬盘可能会在保修期内因低只读工作负载而磨损，因为大量读取干扰导致的重写是在后台执行的。为了了解替代的读取干扰缓解机会，我们还在另外两个没有后台重写机制的固态硬盘上进行了读取延迟特性分析。收集的结果表明，在没有后台重写的情况下，随着对数据的读取次数的增加，大多数数据的读取延迟变得更高。基于这两个特点，本文提出了放宽对高密度3D固态硬盘的短读延迟限制。具体地说，我们的建议依赖于从应用程序传递到SSD的提示信息，该信息指定了预期的读取性能。通过这样做，可以减少由读感应写入引起的寿命消耗，从而延长SSD寿命。详细的实验评估表明，在文件服务器应用程序下，我们的方案可以在仅降低2%的性能的情况下减少高达56%的重写导致的耗用生命周期。
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.