Tandem Capacity Model (TCM) Manual

Capacity History Trend Charts Screen
The TrendCharts sheet has one Trend chart for each transaction name in the History data. Each
Trend chart has two plot areas, one in the top half and one in the bottom half. The top half plots
the CPU Seconds per Transaction. The bottom half plots the TPS rate (if OLTP), or the Transactions
per Task rate (if Batch) and a best-fit linear trend line. Sample dates are on the x-axis and apply
to both halves of the chart.
The Trend chart is designed so you can easily see how transaction rates change over time from
sample to sample and how the corresponding transaction cost (CPU time per transaction) varies
by sample. If a reasonable apportionment scheme was used when adding the data to the History
file, the transaction cost will not vary much from sample to sample and should not be a function
of the sample transaction throughput rate.
The Capacity Planner can use the rate trend line for the trend chart's transaction to estimate future
expected transaction rates for samples beyond those that occur in the History file. The Performance
model already allows for automated linear trend estimation of transaction throughput rates. These
History Trend charts can make it easier for you to see and work with the existing rate trends in
graphical form. For information on creating a Trend chart, see “History Charts” (page 124).
Capacity History Mix Chart Screen
The MixCharts worksheet contains one Mix chart for every sample in the History data. Each Mix
chart is a 3-D pie chart showing the percentage of CPU activity each named transaction consumed
during that data sample. This data is plotted from the Mix column of the History data. For information
on creating a Mix chart, see “History Charts” (page 124).
TCM User Customization Screen
The TCM User Customization screen allows users to modify the appearance of the TCM screens.
Figure 53 (page 160) shows the TCM User Customization screen.
To display this screen, select the Customize TCM option from the Options tab. To return to the TCM
model, click the Return to Model button at the top of this screen.
TCM User Customization Screen 159