STRETCH
-------

STRETCH is a nice little performance analysis program.  It was originally
written for a client with a large Vaxcluster installation who wanted
quantitative answers to capacity questions.  This program was, (or
more correctly, will have been) discussed at the Structured Cluster
Management talk at Fall '86 Decus.  If you are plagued by the "we did
'x', how much did it help..." questions, STRETCH may be able to help you.

Essentially, STRETCH reads a log file that is written periodically
by a job you provide that records the elapsed time taken to
perform some standard benchmark.  This can be as simple as a short
batch job rescheduled every 30 minutes that performs some job mix
characteristic of your installation.  The format of the log file is
succeeding lines of the form:

DD-MMM-YYYY HH:MM:SS.CC   EEEEEEEE VV NNNNNN

The first field is the time stamp, the "EEE..." field is the
integer representing the relative elapsed time (measured in whatever
units pleases you - Stretch doesn't care), and VV and NNNNNN are version
(arbitrary two characters) and node id, both unused in the version of
STRETCH on this tape.

STRETCH is simply a robust analysis program.  It can interval average,
do folded windows (average day, average week), stack bars from different
nodes, normalize and zero-shift, exclude or include certain days and
hours, and in general, give a pretty good trend line assuming your
log data bears some relation to what is really going on.  (I personally
suggest not wasting too much time trying to come up with the ideal
benchmark, most metrics come out pretty similar in a relative sense.)

One word of caution.  STRETCH is intended as a capacity tool.  Although
it is very good at helping to spot trends, it will give you no "why"
information.  For that, you should go to MONITOR, SPM, VMS accounting
logs, uncooperative users, your own intuition, etc.

The documentation and help file is provided, and I won't attempt to
reiterate them here.  I have found STRETCH to be very useful, filling
a void that neither VMS accounting logs, SPM, MONITOR or third-party
products can fill.  I hope you are able to get as much use out of it
as I have.

Steve Duff
05-Oct-1986

Ergodic Systems Inc.
2401 E. 17th St. Suite 190
Santa Ana, Ca. 92701
(714) 542-9155
