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Recon: Verifying file system consistency at runtime

Recon: Verifying file system consistency at runtime Recon: Verifying File System Consistency at Runtime DANIEL FRYER, KUEI SUN, RAHAT MAHMOOD, TINGHAO CHENG, SHAUN BENJAMIN, ASHVIN GOEL, and ANGELA DEMKE BROWN, University of Toronto File system bugs that corrupt metadata on disk are insidious. Existing reliability methods, such as checksums, redundancy, or transactional updates, merely ensure that the corruption is reliably preserved. Typical workarounds, based on using backups or repairing the file system, are painfully slow. Worse, the recovery may result in further corruption. We present Recon, a system that protects file system metadata from buggy file system operations. Our approach leverages file systems that provide crash consistency using transactional updates. We define declarative statements called consistency invariants for a file system. These invariants must be satisfied by each transaction being committed to disk to preserve file system integrity. Recon checks these invariants at commit, thereby minimizing the damage caused by buggy file systems. The major challenges to this approach are specifying invariants and interpreting file system behavior correctly without relying on the file system code. Recon provides a framework for file-system specific metadata interpretation and invariant checking. We show the feasibility of interpreting metadata and writing consistency invariants for the Linux ext3 file system using 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 © 2012 by ACM Inc.
ISSN
1553-3077
DOI
10.1145/2385603.2385608
Publisher site
See Article on Publisher Site

Abstract

Recon: Verifying File System Consistency at Runtime DANIEL FRYER, KUEI SUN, RAHAT MAHMOOD, TINGHAO CHENG, SHAUN BENJAMIN, ASHVIN GOEL, and ANGELA DEMKE BROWN, University of Toronto File system bugs that corrupt metadata on disk are insidious. Existing reliability methods, such as checksums, redundancy, or transactional updates, merely ensure that the corruption is reliably preserved. Typical workarounds, based on using backups or repairing the file system, are painfully slow. Worse, the recovery may result in further corruption. We present Recon, a system that protects file system metadata from buggy file system operations. Our approach leverages file systems that provide crash consistency using transactional updates. We define declarative statements called consistency invariants for a file system. These invariants must be satisfied by each transaction being committed to disk to preserve file system integrity. Recon checks these invariants at commit, thereby minimizing the damage caused by buggy file systems. The major challenges to this approach are specifying invariants and interpreting file system behavior correctly without relying on the file system code. Recon provides a framework for file-system specific metadata interpretation and invariant checking. We show the feasibility of interpreting metadata and writing consistency invariants for the Linux ext3 file system using

Journal

ACM Transactions on Storage (TOS)Association for Computing Machinery

Published: Nov 1, 2012

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