EDC: Improving the Performance and Space Efficiency of Flash-Based Storage Systems with Elastic Data Compression
EDC: Improving the Performance and Space Efficiency of Flash-Based Storage Systems with Elastic Data Compression
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DOI：
10.1109/tpds.2018.2794966
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发表时间：
2018-06
影响因子：
5.3
通讯作者：
Bo Mao;Suzhen Wu;Hong Jiang;Yaodong Yang;Zaifa Xi
中科院分区：
文献类型：
--
作者：
Bo Mao;Suzhen Wu;Hong Jiang;Yaodong Yang;Zaifa Xi
通过利用数据压缩等数据缩减技术，所有基于闪存的存储系统都可以具有与传统基于hdd的存储系统相同的总拥有成本（TCO）。因此，通过减少写流量和空间容量需求，数据压缩已成为闪存存储系统中提高空间效率和可靠性的一种商品特性。但是，它在关键I/O路径上引入了明显的处理开销，从而显著降低了系统性能。现有的基于闪存存储系统的数据压缩方案对所有传入的写数据使用固定的压缩算法，无法识别和利用数据的可压缩性和访问模式的显著多样性，从而错失了提高系统性能或空间效率或两者兼而有之的机会。为了在这两个重要的设计目标之间实现合理的权衡，本文引入了一种称为EDC的弹性数据压缩方案，该方案在利用访问空闲的同时，通过明智地将不同压缩率的数据与不同的压缩算法进行匹配，从而利用数据的可压缩性和访问强度特征。具体来说，对于可压缩的数据块，EDC利用了工作负载的压缩多样性，在系统利用率较低的时间段采用压缩率较高的算法，在系统利用率较高的时间段采用压缩率较低的算法。对于不可压缩（或非常低可压缩）的数据块，它将直接将它们写入闪存，而不进行任何压缩。在我们的轻量级EDC系统原型实现上进行的实验表明，EDC最多节省38.7%的存储空间，平均节省33.7%。此外，在I/O性能测量中，它明显优于固定压缩方案，最高可达61.4%，平均为36.7%。
By leveraging data reduction technologies, such as data compression, all flash-based storage systems can have the same total cost of ownership (TCO) as traditional HDD-based storage systems. Thus, data compression has become a commodity feature for space efficiency and reliability in flash-based storage systems by reducing write traffic and space capacity demand. However, it introduces noticeable processing overheads on the critical I/O path, which degrades the system performance significantly. Existing data compression schemes for flash-based storage systems use fixed compression algorithms for all the incoming write data, failing to recognize and exploit the significant diversity in compressibility and access patterns of data and missing an opportunity to improve the system performance, the space efficiency or both. To achieve a reasonable trade-off between these two important design objectives, in this paper we introduce an Elastic Data Compression scheme, called EDC, which exploits the data compressibility and access intensity characteristics by judiciously matching data of different compressibility with different compression algorithms while leveraging the access idleness. Specifically, for compressible data blocks EDC exploits the compression diversity of the workload, and employs algorithms of higher compression rate in periods of lower system utilization and algorithms of lower compression rate in periods of higher system utilization. For non-compressible (or very lowly compressible) data blocks, it will write them through to the flash storage directly without any compression. The experiments conducted on our lightweight prototype implementation of the EDC system show that EDC saves storage space by up to 38.7 percent, with an average of 33.7 percent . In addition, it significantly outperforms the fixed compression schemes in the I/O performance measure by up to 61.4 percent, with an average of 36.7 percent.