Using transparent compression to improve SSD-based I/O caches

  • Authors:

  • Thanos Makatos;Yannis Klonatos;Manolis Marazakis;Michail D. Flouris;Angelos Bilas

  • Affiliations:

  • Foundation for Research and Technology - Hellas (FORTH), Institute of Computer Science (ICS), Heraklion, Greece;Foundation for Research and Technology - Hellas (FORTH), Institute of Computer Science (ICS), Heraklion, Greece;Foundation for Research and Technology - Hellas (FORTH), Institute of Computer Science (ICS), Heraklion, Greece;Foundation for Research and Technology - Hellas (FORTH), Institute of Computer Science (ICS), Heraklion, Greece;Foundation for Research and Technology - Hellas (FORTH), Institute of Computer Science (ICS), Heraklion, Greece

  • Venue:
  • Proceedings of the 5th European conference on Computer systems
  • Year:
  • 2010

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Abstract

Flash-based solid state drives (SSDs) offer superior performance over hard disks for many workloads. A prominent use of SSDs in modern storage systems is to use these devices as a cache in the I/O path. In this work, we examine how transparent, online I/O compression can be used to increase the capacity of SSD-based caches, thus increasing the costeffectiveness of the system. We present FlaZ, an I/O system that operates at the block-level and is transparent to existing file-systems. To achieve transparent, online compression in the I/O path and maintain high performance, FlaZ, provides support for variable-size blocks, mapping of logical to physical blocks, block allocation, and cleanup. FlaZ, mitigates compression and decompression overheads that can have a significant impact on performance by leveraging modern multicore CPUs. We implement FlaZ, in the Linux kernel and evaluate it on a commodity server with multicore CPUs, using TPC-H, PostMark, and SPECsfs. Our results show that compressed caching trades off CPU cycles for I/O performance and enhances SSD efficiency as a cache by up to 99%, 25%, and 11% for each workload, respectively.