A Trace-Driven Analysis of the UNIX 4.2BSD File System

Abstract

We analyzed the UNIX 4.2BSD file system by recording activity in trace files and writing programs to analyze the traces. The trace analysis shows that the average file system bandwidth needed per user is low (a few hundred bytes per second). Most of the files accessed are short, are open a short time, and are accessed sequentially. Most new information is deleted or overwritten within a few minutes of its creation. We wrote a simulator that uses the traces to predict the performance of caches for disk blocks. The moderate-sized caches used in UNIX reduce disk traffic by about 50%, but larger caches (several megabytes) can achieve much greater reductions, eliminating 90% or more of all disk traffic. With those large caches, large block sizes (16 kbytes or more) result in the fewest disk accesses.

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Document Details

Document Type
Technical Report
Publication Date
Apr 25, 1985
Accession Number
ADA611686

Entities

People

  • David Harrison
  • Herve Da Costa
  • James G. Thompson
  • John A. Kunze
  • John K. Ousterhout
  • Mike Kupfer

Organizations

  • University of California, Berkeley

Tags

Communities of Interest

  • Materials and Manufacturing Processes

DTIC Thesaurus Topics

  • Access Time
  • Computer Science
  • Computers
  • Data Transmission
  • Directories
  • Electrical Engineering
  • Engineering
  • Intervals
  • Measurement
  • Megabytes
  • Networks
  • Operating Systems
  • Servers (Computer Hardware)
  • Simulations
  • Simulators
  • Throughput
  • Urban Areas

Fields of Study

  • Computer science

Readers

  • Computer Science/Computer Engineering/Data Science/Digital Signal Processing.
  • Database Systems and Applications
  • Parallel and Distributed Computing.