Strata: A Cross Media File System
Strata: A Cross Media File System
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DOI：
10.1145/3132747.3132770
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发表时间：
2017-10
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通讯作者：
Youngjin Kwon;Henrique Fingler;T. Hunt;Simon Peter;Emmett Witchel;T. Anderson
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作者：
Youngjin Kwon;Henrique Fingler;T. Hunt;Simon Peter;Emmett Witchel;T. Anderson
当前的硬件和应用程序存储趋势给操作系统的存储子系统带来了巨大的压力。在硬件方面，存储设备的市场已经多样化到多层存储拓扑，其在成本和性能方面跨越多个数量级。在文件系统之上，应用程序越来越需要以低延迟、高吞吐量和简单的崩溃一致性处理大量数据集上的小型随机IO。为单个存储层设计的文件系统无法同时支持所有这些需求。我们提出了Strata，一个跨媒体文件系统，利用一个存储介质的优势，以弥补另一个的弱点。这样，Strata同时提供了性能、容量和简单的同步IO模型，同时具有比受单个存储设备约束的文件系统更简单的设计。Strata的核心是使用日志结构的方法，在用户模式、内核和存储层之间进行了新的职责划分，将可扩展的高性能持久性与存储层管理分开。我们量化的性能优势的Strata使用3层存储层次结构的仿真NVM，基于闪存的SSD和高密度HDD。与专为每层构建的文件系统相比，Strata在几个未经修改的应用程序中的延迟和吞吐量提高了20-30%，同时提供对整个存储层次结构的同步和统一访问。最后，Strata的吞吐量比Linux的逻辑卷管理器提供的基于块的2层缓存高出2.8倍。
Current hardware and application storage trends put immense pressure on the operating system's storage subsystem. On the hardware side, the market for storage devices has diversified to a multi-layer storage topology spanning multiple orders of magnitude in cost and performance. Above the file system, applications increasingly need to process small, random IO on vast data sets with low latency, high throughput, and simple crash consistency. File systems designed for a single storage layer cannot support all of these demands together. We present Strata, a cross-media file system that leverages the strengths of one storage media to compensate for weaknesses of another. In doing so, Strata provides performance, capacity, and a simple, synchronous IO model all at once, while having a simpler design than that of file systems constrained by a single storage device. At its heart, Strata uses a log-structured approach with a novel split of responsibilities among user mode, kernel, and storage layers that separates the concerns of scalable, high-performance persistence from storage layer management. We quantify the performance benefits of Strata using a 3-layer storage hierarchy of emulated NVM, a flash-based SSD, and a high-density HDD. Strata has 20-30% better latency and throughput, across several unmodified applications, compared to file systems purpose-built for each layer, while providing synchronous and unified access to the entire storage hierarchy. Finally, Strata achieves up to 2.8x better throughput than a block-based 2-layer cache provided by Linux's logical volume manager.