Electrical Engineering
      and Computer Sciences

Electrical Engineering and Computer Sciences

COLLEGE OF ENGINEERING

UC Berkeley

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

John K. Ousterhout, Herve Da Costa, David Harrison, John A. Kunze, Michael Kupfer and James G. Thompson

EECS Department
University of California, Berkeley
Technical Report No. UCB/CSD-85-230
April 1985

http://www.eecs.berkeley.edu/Pubs/TechRpts/1985/CSD-85-230.pdf

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.


BibTeX citation:

@techreport{Ousterhout:CSD-85-230,
    Author = {Ousterhout, John K. and Da Costa, Herve and Harrison, David and Kunze, John A. and Kupfer, Michael and Thompson, James G.},
    Title = {A Trace-Driven Analysis of the UNIX 4.2BSD File System},
    Institution = {EECS Department, University of California, Berkeley},
    Year = {1985},
    Month = {Apr},
    URL = {http://www.eecs.berkeley.edu/Pubs/TechRpts/1985/5199.html},
    Number = {UCB/CSD-85-230},
    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.}
}

EndNote citation:

%0 Report
%A Ousterhout, John K.
%A Da Costa, Herve
%A Harrison, David
%A Kunze, John A.
%A Kupfer, Michael
%A Thompson, James G.
%T A Trace-Driven Analysis of the UNIX 4.2BSD File System
%I EECS Department, University of California, Berkeley
%D 1985
%@ UCB/CSD-85-230
%U http://www.eecs.berkeley.edu/Pubs/TechRpts/1985/5199.html
%F Ousterhout:CSD-85-230