Browse Prior Art Database

Real Time, Trace Driven Monitor for File System Performance

IP.com Disclosure Number: IPCOM000122006D
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 3 page(s) / 126K

Publishing Venue

IBM

Related People

Smith, MG: AUTHOR

Abstract

Disclosed is a program which monitors computer file system and I/O system events in real-time, and reports on the performance of all accesses to files, virtual memory segments, logical volumes, and physical volumes over an arbitrarily long measurement period. This monitor, called "filemon", is useful to anyone whose applications are known or believed to be disk-bound (i.e., applications which over-utilize disk resources to the point of poor performance), and wants to know where and why.

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Real Time, Trace Driven Monitor for File System Performance

      Disclosed is a program which monitors computer file
system and I/O system events in real-time, and reports on the
performance of all accesses to files, virtual memory segments,
logical volumes, and physical volumes over an arbitrarily long
measurement period.  This monitor, called "filemon", is useful to
anyone whose applications are known or believed to be disk-bound
(i.e., applications which over-utilize disk resources to the point of
poor performance), and wants to know where and why.

      Filemon is a trace-driven monitor [*].  That is, it computes
file system performance measures and statistics by reading and
analyzing a "trace" (log) of the events which occurred in the file
system while applications  perform file I/O.  Filemon reads and
analyzes the trace continuously and in real-time, so that the
measurement period can be arbitrarily long.

      (The trace facility used by filemon may already be provided as
part of the operating system, e.g., as in the AIX* operating system.)

      The main advantages of filemon are:
      (1) It captures and relates events at all levels of the file
system; e.g., in the AIX operating system, it monitors accesses at
the logical file  level, virtual memory segment level, logical volume
level, and physical  volume level. Consequently, it will relate the
activity between each of the levels--logical file accesses can be
related to virtual memory  accesses, which are then related to
logical and physical volume accesses.  This provides a complete
"picture" of file system performance and behavior to a user or
analyst than the standard utilities available in AIX or other UNIX**
operating systems.
      (2) It provides a comprehensive set of statistics about
accesses to files,  virtual memory, logical volumes, and physical
volumes.  For example,  it maintains statistics about the
distributions of retrieval response times, seek distances, queue
lengths, etc.  These statistics are more comprehensive than those
provided by the standard utilities in AIX or other UNIX operating
systems.  Computation of these statistics is facilitated by the trace
data.
FUNCTIONAL DESCRIPTION OF PROGRAM

      In its normal mode, filemon runs in the background while  one
or more application programs or system commands are  being  executed
and monitored.   Filemon automatically starts and monitors a trace of
the programs' file system and I/O events in real time.  By default,
the trace is started immediately; optionally, tracing may be deferred
until the user issues a "start trace" command.  The user can issue
"start trace" and "stop trace" commands while filemon is running in
order to turn off and on monitoring, as desired.  When tracing is
stopped via a "stop trace" command, filemon generates an I/O activity
report and exits.

      Optionally, filemon can process a trace file which has been
previously recorded...