Tandem Capacity Model (TCM) Manual

For example, in a Pathway application, the default table would assume that the number of
transactions is equal to the number of messages received by its Pathway server class.
Although the default algorithm is frequently accurate, in some cases it will need to be modified.
A value of zero in the matrix indicates that messages received (or sent) by the category should
not be counted as transactions. A value of n indicates that the WA model should multiply by
n the number of messages received (or sent) by the category in calculating the number of
transactions.
TCM issues a warning if the transaction count matrix contains all zeros for any transaction.
Maximum Transactions
The maximum number of transactions that can be modeled is 40. Procedures for creating and
modifying the Transaction Count table are similar to the procedures for creating and modifying
the Apportionment Weights table. For details, see “Workload Apportionment Weights Table”
(page 116).
Transaction Count Table Versus Transaction Count File
You can create a Transaction Count file to compute the number of transactions instead of using
the counts in the Transaction Count table. This feature is useful if you know how many transactions
are processed by your application.
For example, you might be able to create a simple program to parse your application’s statistics
or log file to determine the number of transactions processed by your application. Alternately, you
can use Measure user-defined counters to determine the number of transactions processed by your
application. You can create the file on the NonStop host system and download the file to the custom
folder, or you can create the file directly on the PC.
When TCM loads a CSV file, it checks to see if the corresponding Transaction Count file exists. If
the Transaction Count file exists, TCM uses the Transaction Count file for the transaction counts
and uses the Transaction Count table if any transaction counts are missing in the Transaction Count
file. Thus, you can use both a Transaction Count table and Transaction Count files. If you use both,
the values in the Transaction Count files supersede any values in the Transaction Count table.
For example, suppose your application has 20 transactions, and you have counts for 8 of the
transactions. You can use Transaction Count files to indicate the counts for these 8 transactions.
You should not put blanks in the Transaction Count files. For the 12 transactions not listed in the
Transaction Count files, TCM uses the Transaction Count table for the counts.
Transaction Count File Naming Convention
You create a Transaction Count file with a name patterned after the CSV file name. The Transaction
Count file has the same name as the CSV file except the extension is .TCF instead of .CSV.
For example, the CSV file EXAMPLE1.CSV would become Transaction Count file EXAMPLE1.TCF.
The Workload Apportionment model uses the counts in the Transaction Count file instead of its
generated formulas to calculate the number of transactions. When you load category data, TCM
automatically detects when you have a Transaction Count file and loads it.
Transaction Count File Format
The Transaction Count file has the following format:
TXNCNT
txn-name-1, txn-cnt-1, comment text
txn-name-2, txn-cnt-2, comment text
For example, a valid Transaction Count file follows:
TXNCNT
BIG, 500, You have 500 transactions of type BIG
ST1, 10, You have 10 ST1 transactions
120 Workload Apportionment Model