Tandem Capacity Model (TCM) Manual

The Rcv/Send counts for each transaction name are multiplied by the user-entered coefficients and
summed to produce a transaction count. In the example, the number of Deposit transactions is set
equal to 1 times the messages received by the Deposit category.
The following guidelines apply to the Transaction Count table:
• Entries can be positive or negative.
• Entries can be decimal fractions, such as 0.5.
• Transaction counts are calculated as a sum of Send/Receive message counts multiplied by
the entries in the two columns below the transaction name.
For example, if there are 2 sends from the Deposit category for each Deposit transaction, you
would enter 0.5 in the table rather than a 1. Transaction counts are computed by multiplying
message counts by the numbers in the table. Therefore, two messages per transaction requires
0.5 in the table, not 2.
• Most entries of the Transaction Count table are zero (0). This scenario is typical of real world
situations. To count transactions, you usually do not have to trace every interprocess message.
You need only identify the places where a simple relationship exists between category message
traffic and transaction counts.
The Transaction Count table for the example follows:
Once created, the TCM administrator can modify the default apportionment tables to create one
or more apportionment methods that are well suited to the particular application. The tables are
then saved as part of your WA model, which you can use to apportion a variety of performance
data samples.
Transaction Count Table Versus Transaction Count File
CAUTION: Modifying these values is not recommended. Edit these protected cells carefully in
order not to overwrite some of the default formulas.
Apportionment Tables 73