Trend
analysis graphics are based on performance history files 'ACUM HISTSUM'
or 'ACUM PERFHIST'. Depending on the selected period, the average
load for one day or for several days will be represented by a single
plot position, thus allowing periods of several months or even years
to be included in a single display. The resulting graphics can so
show performance trends over long periods, and they are a good basis
for capacity planning. Figure 1. Layout of performance
trend display (GDDM)
The above example has been created
by entering the command 'GRAPHS CPU IO/S FI ACUM PERFHIST FR 010103
TO 122303 H 8 9 10 14 15 16', i.e. the trends for total CPU load and
the I/O request rate have been plotted for the year 2003. The 'HOURS'
selection has been added to make sure that the resulting graphics
show the trends for heavily loaded periods of the day only (averages
which include many hours of low activity are of little help for capacity
planning).
Be careful and make sure you are really plotting the data you want:
All days found within the selected period are going to contribute
to our trend graphics. Suppress weekends by specifying the DAYS argument
of the GRAPHSUM command, and delete other records for days with non-representative
load (such as the public holidays of January 1/2 and Easter in the
example), if necessary, before generating trend graphics which are
to serve as a base for capacity planning.
All hours for which data are available in any given day will contribute
to this day's average unless you specify the 'HOURS' argument of the
GRAPHSUM or PLOTSUM command. If your history file includes data from
many hours with low activity, these will cause correspondingly low
averages to be generated if you do not explicitely select peak hours.
See GRAPHSUM / PLOTSUM for a detailed description
of the GRAPHSUM command.
