An Empirical Study of FTL Performance in Conjunction with File System Pursuing Data Integrity

In Hwan DOH  Myoung Sub SHIM  Eunsam KIM  Jongmoo CHOI  Donghee LEE  Sam H. NOH  

Publication
IEICE TRANSACTIONS on Information and Systems   Vol.E93-D   No.8   pp.2302-2305
Publication Date: 2010/08/01
Online ISSN: 1745-1361
DOI: 10.1587/transinf.E93.D.2302
Print ISSN: 0916-8532
Type of Manuscript: LETTER
Category: Software System
Keyword: 
Flash Translation Layer (FTL),  flash memory,  file system,  metadata,  non-volatile RAM,  write cache,  

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Summary: 
Due to the detachability of Flash storage, which is a dominant portable storage, data integrity stored in Flash storages becomes an important issue. This study considers the performance of Flash Translation Layer (FTL) schemes embedded in Flash storages in conjunction with file system behavior that pursue high data integrity. To assure extreme data integrity, file systems synchronously write all file data to storage accompanying hot write references. In this study, we concentrate on the effect of hot write references on Flash storage, and we consider the effect of absorbing the hot write references via nonvolatile write cache on the performance of the FTL schemes in Flash storage. In so doing, we quantify the performance of typical FTL schemes for a realistic digital camera workload that contains hot write references through experiments on a real system environment. Results show that for the workload with hot write references FTL performance does not conform with previously reported studies. We also conclude that the impact of the underlying FTL schemes on the performance of Flash storage is dramatically reduced by absorbing the hot write references via nonvolatile write cache.