NDLI: Azor: Using Two-Level Block Selection to Improve SSD-Based I/O Caches

Content Provider	IEEE Xplore Digital Library
Author	Klonatos, Y. Makatos, T. Marazakis, M. Flouris, M.D. Bilas, A.
Copyright Year	2011
Abstract	Flash-based solid state drives (SSDs) exhibit potential for solving I/O bottlenecks by offering superior performance over hard disks for several workloads. In this work we design Azor, an SSD-based I/O cache that operates at the block-level and is transparent to existing applications, such as databases. Our design provides various choices for associativity, write policies and cache line size, while maintaining a high degree of I/O concurrency. Our main contribution is that we explore differentiation of HDD blocks according to their expected importance on system performance. We design and analyze a two-level block selection scheme that dynamically differentiates HDD blocks, and selectively places them in the limited space of the SSD cache. We implement Azor in the Linux kernel and evaluate its effectiveness experimentally using a server-type platform and large problem sizes with three I/O intensive workloads: TPC-H, SPECsfs 2008, and Hammerora. Our results show that as the cache size increases, Azor enhances I/O performance by up to 14.02×, 1.63×, and 1.55× for each workload respectively. Additionally, our two-level block selection scheme further enhances I/O performance compared to a typical SSD cache by up to 95%, 16%, and 34% for each workload, respectively.
Starting Page	309
Ending Page	318
File Size	398018
Page Count	10
File Format	PDF
ISBN	9781457711725
e-ISBN	9780769545097
DOI	10.1109/NAS.2011.50
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2011-07-28
Publisher Place	China
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Evaluation Databases Memory management Random access memory Solid State Disk (SSD) caches Aerospace electronics Benchmark testing Throughput I/O performance Servers
Content Type	Text
Resource Type	Article

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