Tandem Capacity Model (TCM) Manual

Actual data based on the workload-apportioned Measure data appears in the Actual column.
Default constraints appear in the Constraint column. The configuration recommended by TCM
appears in the Plan column.
3. Enter constraints in the input fields in the Constraint column and other highlighted cells. Then
press Return.
4. After entering all of the changes you want into the highlighted input fields, press Return. Then
select Options > Calculate Now. To finish entering your data, you must press Return before
selecting Calculate Now or pressing a function key.
TCM calculates all the values in the Plan column to support the given constraints.
About the Results
As a starting point TCM recommends a reasonable combination of CPUs and disks at an estimated
minimum cost. For a definitive solution you must analyze your system environment and budgetary
constraints to determine the optimal combination of CPUs and disks. If this analysis shows it is
impossible to support a given workload within your constraints, TCM flags the Plan or Constraint
fields corresponding to the unachievable constraints.
Using the Planning Timeline Model
The TCM Planning Timeline model is used to examine host response times and throughputs over
six user-specified planning periods. You can specify several growth scenarios including:
• Throughput growth rate for OLTP transactions (Rate column) starts from the second column.
The first column is the actual for the Basic Sample Data for the Consumption model.
• Number of transactions per tasks growth rate for batch transactions (Rate column)
• Number of CPUs, disks or both over time
• CPU and disk type
You can display the results of the Planning Timeline model in a chart and print the chart. Default
behavior from the Planning Timeline line propagates to the right from column 2. The user can
define behavior changes.
To use the Planning Timeline model:
1. Open a Performance model.
2. Choose Find > Planning Timeline. The Planning Timeline model appears. Figure 25 (page 92)
shows a sample Planning Timeline model.
Using the Planning Timeline Model 91