Adaptive Switch on Wear Leveling for Enhancing I/O Latency and Lifetime of High-density SSDs
Adaptive Switch on Wear Leveling for Enhancing I/O Latency and Lifetime of High-density SSDs
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磨损均衡的自适应开关可提高高密度 SSD 的 I/O 延迟和使用寿命
DOI：
10.1109/tcad.2022.3197340
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发表时间：
2022
影响因子：
2.9
通讯作者：
Jianwei Liao
中科院分区：
文献类型：
--
作者：
Jiaojiao Wu;Jun Li;Zhibing Sha;Zhigang Cai;Jianwei Liao
基于 NAND 闪存的高密度 SSD 通常具有有限的写入耐久性，因为单个块在有限数量的编程/擦除周期后变得不可用。 （静态）磨损均衡算法将冷数据迁移到磨损较多的块，以在 SSD 中产生均匀的磨损分布。然而，迁移冷数据必须延迟正常的 I/O 处理，并且不必要的磨损均衡操作可能会损害 SSD 的耐用性，因为每个操作都会导致编程/擦除周期。本文提出了一种自适应磨损均衡开关（称为 ASWL），以提高高密度 SSD 的 I/O 性能和使用寿命。 ASWL的基本思想是自适应切换阈值函数，在SSD寿命的不同阶段智能触发磨损均衡操作。为此，我们考虑I/O强度和SSD块磨损差异的实时因素，建立了动态确定磨损均衡阈值条件的数学模型。通过对几个真实磁盘轨迹的一系列仿真实验，我们表明，与现有的磨损均衡方法相比，所提出的 ASWL 机制不仅可以极大地提高 I/O 性能，而且可以显着延长高密度 SSD 的使用寿命。
NAND flash-based high-density SSDs commonly have limited write endurance, as a single block becomes unavailable after a finite number of program/erase cycles. The (static) wear leveling algorithms migrate cold data to more worn blocks for yielding an even distribution of wears in SSDs. However, migrating cold data must delay normal I/O processing, and unnecessary wear leveling operations may damage SSD endurance as each operation causes a program/erase cycle. This paper proposes an adaptive switch on wear leveling (called as ASWL), to boost I/O performance and lifetime for high-density SSDs. The basic idea of ASWL is to adaptively switch the threshold function for intelligently triggering wear leveling operations at different stages of SSD lifetime. To this end, we build a mathematical model determining the wear leveling threshold condition with a dynamic manner, by considering the real-time factors of I/O intensity and the wear difference of SSD blocks. Through a series of emulation experiments on several realistic disk traces, we show that the proposed ASWL mechanism cannot only greatly improve I/O performance, but also noticeably extend the lifetime of high-density SSDs, in contrast to existing wear leveling methods.