DHeating: Dispersed heating repair for self-healing NAND flash memory
DHeating: Dispersed heating repair for self-healing NAND flash memory
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DOI：
10.1109/codes-isss.2013.6658994
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发表时间：
2013-09
期刊：
影响因子：
--
通讯作者：
Renhai Chen;Yi Wang;Z. Shao
中科院分区：
文献类型：
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作者：
Renhai Chen;Yi Wang;Z. Shao
随着多电平单元和三电平单元闪存的出现，短寿命正成为NAND闪存中的关键问题。Macronix的研究人员最近发现，加热可以使磨损的NAND闪存单元变得可重复使用，并大大延长闪存单元的寿命。然而，加热过程消耗大量的功率。这意味着，如果要将现有的NAND闪存管理技术应用于自修复NAND闪存，则需要进行一些根本性的改变。特别是，所有现有的磨损均衡技术都是基于均匀分布写入和擦除的原则。这导致NAND闪存单元往往在短时间内磨损。此外，以集中的方式修复这些小区可能导致移动的设备中的断电。本文首次提出了一种新的损耗均衡机制--分散加热机制（DHeating，DispersedHeating），以解决自修复闪存中的集中加热问题。在DHeating中，不是在一段时间内均匀地分布写入和擦除，而是将写入和擦除操作集中在闪存单元的一小部分上，使得这些单元可以通过首先加热而磨损和修复。这样，我们可以分散治疗，以避免因加热而导致的集中用电问题。此外，由于自修复导致的非常长的寿命，我们可以牺牲寿命来换取可靠性。因此，我们提出了一个早期加热策略，以解决集中加热所带来的可靠性问题。我们的想法是通过在NAND闪存单元的预期耐久性之前加热它们来更早地开始修复过程。我们评估我们的计划基于一个真实的嵌入式平台。实验结果表明，该方案能有效地解决集中供热问题。
Short lifetimes are becoming a critical issue in NAND flash memory with the advent of multi-level cell and triple-level cell flash memory. Researchers at Macronix have recently discovered that heating can cause worn-out NAND flash cells to become reusable and greatly prolong the lifetime of flash memory cells. However, the heating process consumes a substantial amount of power. This means that some fundamental changes are required if existing NAND flash management techniques are to be applied in self-healing NAND flash memory. In particular, all existing wear-leveling techniques are based on the principle of evenly distributing writes and erases. This causes NAND flash cells tend to wear out in a short time period. Moreover, healing these cells in a concentrated manner may cause power outages in mobile devices. In this paper, we propose for the first time a new wear-leveling scheme called DHeating (Dispersed Heating) to solve the concentrated heating problem in self-healing flash memory. In DHeating, rather than evenly distributing writes and erases over a time period, write and erase operations are concentrated on a small portion of flash memory cells, so that these cells can be worn-out and healed by heating first. In this way, we can disperse healing to avoid the problem of concentrated power usage caused by heating. Furthermore, with the very long lifetime that results from self-healing, we can sacrifice lifetime for reliability. Therefore, we propose an early heating strategy to solve the reliability problem caused by concentrated heating. The idea is to start the healing process earlier by heating NAND flash cells before their expected endurance. We evaluate our scheme based on a real embedded platform. The experimental results show that our scheme can effectively solve the concentrated heating problem.