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Ffsck: The Fast File-System Checker

Ffsck: The Fast File-System Checker Ffsck: The Fast File-System Checker AO MA, University of Wisconsin, Madison and EMC Corporation CHRIS DRAGGA, ANDREA C. ARPACI-DUSSEAU, and REMZI H. ARPACI-DUSSEAU, University of Wisconsin, Madison MARSHALL KIRK MCKUSICK, McKusick.com Failures, errors, and bugs can corrupt file systems and cause data loss, despite the presence of journals and similar preventive techniques. While consistency checkers such as fsck can detect corruption and repair a damaged image, they are generally created as an afterthought, to be run only at rare intervals. Thus, checkers operate slowly, causing significant downtime for large scale storage systems. We address this dilemma by treating the checker as a key component of the overall file system, rather than a peripheral add-on. To this end, we present a modified ext3 file system, rext3, to directly support the fast file-system checker, ffsck. Rext3 colocates and self-identifies its metadata blocks, removing the need for costly seeks and tree traversals during checking. These modifications allow ffsck to scan and repair the file system at rates approaching the full sequential bandwidth of the underlying device. In addition, we demonstrate that rext3 generally performs competitively with ext3 and exceeds it in handling random reads and large writes. Finally, we apply our http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png ACM Transactions on Storage (TOS) Association for Computing Machinery

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Publisher
Association for Computing Machinery
Copyright
Copyright © 2014 by ACM Inc.
ISSN
1553-3077
DOI
10.1145/2560011
Publisher site
See Article on Publisher Site

Abstract

Ffsck: The Fast File-System Checker AO MA, University of Wisconsin, Madison and EMC Corporation CHRIS DRAGGA, ANDREA C. ARPACI-DUSSEAU, and REMZI H. ARPACI-DUSSEAU, University of Wisconsin, Madison MARSHALL KIRK MCKUSICK, McKusick.com Failures, errors, and bugs can corrupt file systems and cause data loss, despite the presence of journals and similar preventive techniques. While consistency checkers such as fsck can detect corruption and repair a damaged image, they are generally created as an afterthought, to be run only at rare intervals. Thus, checkers operate slowly, causing significant downtime for large scale storage systems. We address this dilemma by treating the checker as a key component of the overall file system, rather than a peripheral add-on. To this end, we present a modified ext3 file system, rext3, to directly support the fast file-system checker, ffsck. Rext3 colocates and self-identifies its metadata blocks, removing the need for costly seeks and tree traversals during checking. These modifications allow ffsck to scan and repair the file system at rates approaching the full sequential bandwidth of the underlying device. In addition, we demonstrate that rext3 generally performs competitively with ext3 and exceeds it in handling random reads and large writes. Finally, we apply our

Journal

ACM Transactions on Storage (TOS)Association for Computing Machinery

Published: Jan 1, 2014

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