DFTL: A flash translation layer employing demand-based caching of page-level address mappings

Aayush Gupta, Youngjae Kim, Bhuvan Urgaonkar

Research output: Chapter in Book/Report/Conference proceedingConference contribution

191 Scopus citations

Abstract

Recent technological advances in the development of flashmemory based devices have consolidated their leadership position as the preferred storage media in the embedded systems market and opened new vistas for deployment in enterprise-scale storage systems. Unlike hard disks, flash devices are free from any mechanical moving parts, have no seek or rotational delays and consume lower power. However, the internal idiosyncrasies of flash technology make its performance highly dependent on workload characteristics.The poor performance of random writes has been a cause of major concern which needs to be addressed to better utilize the potential of flash in enterprise-scale environments. We examine one of the important causes of this poor performance: the design of the Flash Translation Layer (FTL) which performs the virtual-to-physical address translations and hides the erase-before-write characteristics of flash. We propose a complete paradigm shift in the design of the core FTL engine from the existing techniques with our Demand-based Flash Translation Layer (DFTL) which selectively caches page-level address mappings.We develope a flash simulation framework called FlashSim. Our experimental evaluation with realistic enterprise-scale workloads endorses the utility of DFTL in enterprise-scale storage systems by demonstrating: (i) improved performance, (ii) reduced garbage collection overhead and (iii) better overload behavior compared to state-of-the-art FTL schemes.For example, a predominantly random-write dominant I/O trace from an OLTP application running at a large financial institution shows a 78% improvement in average response time (due to a 3-fold reduction in operations of the garbage col-lector), compared to a state-of-the-art FTL scheme. Even for the well-known read-dominant TPC-H benchmark, for which DFTL introduces additional overheads, we improve system response time by 56%.

Original languageEnglish (US)
Title of host publicationProceedings of the 14th International Conference on Architectural Support for Programming Languages and Operating Systems, ASPLOS-14
PublisherAssociation for Computing Machinery (ACM)
Pages229-240
Number of pages12
ISBN (Print)9781605584065
DOIs
StatePublished - Jan 1 2009
Event14th International Conference on Architectural Support for Programming Languages and Operating Systems, ASPLOS-14 - Washington, DC, United States
Duration: Mar 7 2009Mar 11 2009

Publication series

NameInternational Conference on Architectural Support for Programming Languages and Operating Systems - ASPLOS

Other

Other14th International Conference on Architectural Support for Programming Languages and Operating Systems, ASPLOS-14
CountryUnited States
CityWashington, DC
Period3/7/093/11/09

All Science Journal Classification (ASJC) codes

  • Software
  • Information Systems
  • Hardware and Architecture

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    Gupta, A., Kim, Y., & Urgaonkar, B. (2009). DFTL: A flash translation layer employing demand-based caching of page-level address mappings. In Proceedings of the 14th International Conference on Architectural Support for Programming Languages and Operating Systems, ASPLOS-14 (pp. 229-240). (International Conference on Architectural Support for Programming Languages and Operating Systems - ASPLOS). Association for Computing Machinery (ACM). https://doi.org/10.1145/1508244.1508271