FAST '04 Abstract
Pp. 115-128 of the Proceedings
A Versatile and User-Oriented Versioning File System
Kiran-Kumar Muniswamy-Reddy, Charles P. Wright, Andrew Himmer, and Erez Zadok, Stony Brook University
File versioning is a useful technique for recording a history of
changes. Applications of versioning include backups and disaster
recovery, as well as monitoring intruders' activities.
Alas, modern systems do not include an automatic and easy-to-use file
versioning system. Existing backup solutions are slow and inflexible
for users. Even worse, they often lack backups for the most recent
day's activities. Online disk snapshotting systems offer more
fine-grained versioning, but still do not record the most recent
changes to files.
Moreover, existing systems also do not give individual users the
flexibility to control versioning policies.
We designed a lightweight user-oriented versioning file system called
Versionfs. Versionfs works with any file system and provides
a host of user-configurable policies: versioning by users, groups,
processes, or file names and extensions; version retention policies
and version storage policies. Versionfs creates file versions
automatically, transparently, and in a file-system portable
manner-while maintaining Unix semantics.
A set of user-level utilities allow administrators to configure and
enforce default policies: users can set policies within configured
boundaries, as well as view, control, and recover files and their
We have implemented the system on Linux. Our performance evaluation
demonstrates overheads that are not noticeable by users under normal
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