With the emerge of high-density triple-level-cell (TLC) and 3D NAND flash, the access performance and endurance of flash devices are degraded due to the downscaling of flash cells. In addition, we observe that the mismatch between data lifetime requirement and flash block retention capability could further worsen the access performance and endurance. This is because the “lifetime-retention mismatch” could result in massive internal data migrations during garbage collection and data refreshing, and further aggravate the already-worsened access performance and endurance of high-density NAND flash devices. Such an observation motivates us to resolve the lifetime-retention mismatch problem by proposing a “time harmonization strategy”, which coordinates the flash block retention capability with the data lifetime requirement to enhance the performance of flash devices with very limited endurance degradation. Specifically, this study aims to lower the amount of internal data migrations caused by garbage collection and data refreshing via storing data of different lifetime requirement in flash blocks with suitable retention capability. The trace-driven evaluation results reveal that the proposed design can effectively reduce the average response time by about 99 percent on average without sacrificing the overall endurance, as compared with the state-of-the-art designs.

中文翻译：

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通过终生保存协调最小化闪存设备的内部数据迁移

随着高密度三级单元（TLC）和3D NAND闪存的出现，由于闪存单元的尺寸缩小，闪存设备的访问性能和耐用性下降。此外，我们观察到数据寿命要求和闪存块保留能力之间的不匹配可能会进一步恶化访问性能和耐用性。这是因为“终身保留失配”可能导致垃圾收集和数据刷新期间大量内部数据迁移，并进一步加剧本来就很糟糕的访问性能和高密度NAND闪存设备的耐用性。这种观察促使我们通过提出“时间协调策略”来解决寿命保留不匹配问题，它使闪存块保留能力与数据寿命要求相协调，以增强闪存设备的性能，而耐久性下降非常有限。具体而言，本研究旨在通过将具有不同寿命要求的数据存储在具有适当保留能力的闪存块中，以减少由垃圾回收和数据刷新引起的内部数据迁移量。跟踪驱动的评估结果表明，与最新设计相比，所提出的设计可以有效地将平均响应时间平均缩短约99％，而不会牺牲整体耐用性。本研究旨在通过将具有不同寿命要求的数据存储在具有适当保留能力的闪存块中，以减少由垃圾回收和数据刷新引起的内部数据迁移量。跟踪驱动的评估结果表明，与最新设计相比，所提出的设计可以有效地将平均响应时间平均缩短约99％，而不会牺牲整体耐用性。本研究旨在通过将具有不同寿命要求的数据存储在具有适当保留能力的闪存块中，以减少由垃圾回收和数据刷新引起的内部数据迁移量。跟踪驱动的评估结果表明，与最新设计相比，所提出的设计可以有效地将平均响应时间平均缩短约99％，而不会牺牲整体耐用性。