Hystor: making the best use of solid state drives in high performance storage systems
Hystor: making the best use of solid state drives in high performance storage systems
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DOI：
10.1145/1995896.1995902
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发表时间：
2011-05
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影响因子：
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通讯作者：
Feng Chen;David A. Koufaty;Xiaodong Zhang
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文献类型：
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作者：
Feng Chen;David A. Koufaty;Xiaodong Zhang
随着技术的快速进步，基于闪存的固态硬盘（SSD）正在成为计算机存储层次结构的重要组成部分，以显着提高性能和能源效率。然而，由于其相对较高的价格和较低的容量，一个主要的系统研究问题，以解决如何使固态硬盘发挥其最有效的作用，在一个高性能的存储系统中，在成本和性能有效的方式。在本文中，我们将回答几个相关的问题与见解的基础上设计和实现的高性能混合存储系统，称为Hystor。我们通过从系统部署和算法设计的角度实现一组优化目标，在存储系统中充分利用SSD。Hystor将SSD和硬盘驱动器（HDD）作为一个单一的块设备进行管理，对现有操作系统内核的更改最小。通过在运行时监控I/O访问模式，Hystor可以有效地识别（1）可能导致长延迟或（2）语义关键的块（例如文件系统元数据），并将其存储在SSD中以供将来访问，从而实现显着的性能提升。为了进一步利用最先进的SSD中异常高的写入性能，Hystor还用作回写缓冲区，以加快写入请求。我们对在Linux内核2.6.25.8中实现的Hystor的测量表明，它可以利用SSD的性能优势，只需对Linux内核进行几行更改。我们的系统研究表明，在一个高效的混合存储系统中，固态硬盘应该发挥重要作用，作为一个独立的存储，最适合的数据是自适应和及时迁移和保留，它也可以有效地作为一个写回缓冲区。
With the fast technical improvement, flash memory based Solid State Drives (SSDs) are becoming an important part of the computer storage hierarchy to significantly improve performance and energy efficiency. However, due to its relatively high price and low capacity, a major system research issue to address is on how to make SSDs play their most effective roles in a high-performance storage system in cost- and performance-effective ways. In this paper, we will answer several related questions with insights based on the design and implementation of a high performance hybrid storage system, called Hystor. We make the best use of SSDs in storage systems by achieving a set of optimization objectives from both system deployment and algorithm design perspectives. Hystor manages both SSDs and hard disk drives (HDDs) as one single block device with minimal changes to existing OS kernels. By monitoring I/O access patterns at runtime, Hystor can effectively identify blocks that (1) can result in long latencies or (2) are semantically critical (e.g. file system metadata), and stores them in SSDs for future accesses to achieve a significant performance improvement. In order to further leverage the exceptionally high performance of writes in the state-of-the-art SSDs, Hystor also serves as a write-back buffer to speed up write requests. Our measurements on Hystor implemented in the Linux kernel 2.6.25.8 show that it can take advantage of the performance merits of SSDs with only a few lines of changes to the stock Linux kernel. Our system study shows that in a highly effective hybrid storage system, SSDs should play a major role as an independent storage where the best suitable data are adaptively and timely migrated in and retained, and it can also be effective to serve as a write-back buffer.