We propose a new I/O architecture for NAND flash-based SSDs, called application-managed flash (AMF) and present two case studies to show its usefulness. In a typical SSD controller, an intermediate software layer, called the flash translation layer (FTL), is employed between NAND flash chips and a host interface. The main responsibility of an FTL is to provide interoperability with conventional HDDs, but this interoperability comes at the cost of extra hardware resources and degraded I/O performance. The proposed AMF refactors the flash storage architecture so that an SSD controller exposes append-only segments, which do not permit overwriting. This refactoring dramatically improves performance of applications and reduces hardware costs by allowing applications to directly manage flash storage with minimal supports from the SSD controller. In order to understand the benefits of AMF, we study two popular applications: a log-structured file system (F2FS) and a key-value store (RocksDB). Our experiments show that the DRAM in the flash controller is reduced by 128X and the performances of the file system and the key-value store improve by 80 and 54 percent, respectively, over conventional SSDs.

中文翻译：

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应用程序管理的 Flash 案例

我们为基于 NAND 闪存的 SSD 提出了一种新的 I/O 架构，称为应用管理闪存 (AMF)，并展示了两个案例研究来展示其实用性。在典型的 SSD 控制器中，在 NAND 闪存芯片和主机接口之间采用称为闪存转换层 (FTL) 的中间软件层。FTL 的主要职责是提供与传统 HDD 的互操作性，但这种互操作性是以额外的硬件资源和 I/O 性能下降为代价的。提议的 AMF 重构了闪存存储架构，以便 SSD 控制器公开不允许覆盖的仅附加段。这种重构通过允许应用程序直接管理闪存存储而从 SSD 控制器获得最少支持，从而显着提高了应用程序的性能并降低了硬件成本。为了理解 AMF 的好处，我们研究了两个流行的应用程序：日志结构文件系统 (F2FS) 和键值存储 (RocksDB)。我们的实验表明，与传统 SSD 相比，闪存控制器中的 DRAM 减少了 128 倍，文件系统和键值存储的性能分别提高了 80% 和 54%。