This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: A Fast File System for UNIX* Marshall Kirk McKusick, William N. Joy, Samuel J. Leffler, Robert S. Fabry Computer Systems Research Group Computer Science Division Department of Electrical Engineering and Computer Science University of California, Berkeley Berkeley, CA 94720 ABSTRACT A reimplementation of the UNIX file system is described. The reimplementation provides substantially higher throughput rates by using more flexible allocation policies that allow better locality of reference and can be adapted to a wide range of peripheral and processor characteristics. The new file system clusters data that is sequentially accessed and provides two block sizes to allow fast access to large files while not wasting large amounts of space for small files. File access rates of up to ten times faster than the traditional UNIX file system are experienced. Long needed enhancements to the pro- grammers interface are discussed. These include a mechanism to place advisory locks on files, extensions of the name space across file systems, the ability to use long file names, and provisions for administrative control of resource usage. Revised February 18, 1984 CR Categories and Subject Descriptors: D.4.3 [Operating Systems] : File Systems Management - file organization, directory structures, access methods ; D.4.2 [Operating Systems] : Storage Management - allocation/deallocation strategies, secondary storage devices ; D.4.8 [Operating Systems] : Performance - measurements, operational analysis ; H.3.2 [Information Systems] : Information Storage - file organization Additional Keywords and Phrases: UNIX, file system organization, file system performance, file system design, application program interface. General Terms: file system, measurement, performance. * UNIX is a trademark of Bell Laboratories. William N. Joy is currently employed by: Sun Microsystems, Inc, 2550 Garcia Avenue, Mountain View, CA 94043 Samuel J. Leffler is currently employed by: Lucasfilm Ltd., PO Box 2009, San Rafael, CA 94912 This work was done under grants from the National Science Foundation under grant MCS80-05144, and the Defense Advance Research Projects Agency (DoD) under ARPA Order No. 4031 monitored by Naval Elec- tronic System Command under Contract No. N00039-82-C-0235. SMM:05-2 A Fast File System for UNIX TABLE OF CONTENTS 1. Introduction 2. Old file system 3. New file system organization 3.1. Optimizing storage utilization 3.2. File system parameterization 3.3. Layout policies 4. Performance 5. File system functional enhancements 5.1. Long file names 5.2. File locking 5.3. Symbolic links 5.4. Rename 5.5. Quotas Acknowledgements References 1. Introduction This paper describes the changes from the original 512 byte UNIX file system to the new one released with the 4.2 Berkeley Software Distribution. It presents the motivations for the changes, the meth- ods used to effect these changes, the rationale behind the design decisions, and a description of the new implementation. This discussion is followed by a summary of the results that have been obtained, direc-implementation....
View Full Document