Tandem Capacity Model (TCM) Manual

check workload apportionment methods that translate process-oriented performance data into
transaction demands. In addition to the basic TCM functions, TCM administrators have access
to the TCM administrative functions and can directly modify more data in the models than
capacity planners.
• Super users
Super users can do everything that TCM administrators can do, and they also have the authority
to resecure the model to gain access to all fields within TCM. Super users need to understand
the internal operation of TCM and must have a good knowledge of Excel.
The TCM functions performed by TCM administrators and super users are passwordprotected. For
information about TCM security, see “Security” (page 68).
TCM and the Capacity Planning Process
This section describes how TCM fits into the capacity planning process.
The seven main steps in the capacity planning process are:
1. “Understanding the Application” (page 21)
2. “Tuning the System” (page 22)
3. “Collecting Performance Data” (page 22)
4. “Apportioning Performance Data” (page 23)
5. “Checking an Apportionment Method” (page 23)
6. “Performing What-If Analyses” (page 23)
7. “Reporting Results” (page 24)
Understanding the Application
To begin the capacity planning process with TCM, you must understand the application.
The capacity planner must have good knowledge of the structure of the application to be modeled,
including an understanding of the major transactions involved and how they flow through the
application. Develop a process flow diagram for each transaction and apportionment methods for
relating process category information (collected on the NonStop host system) to transaction
information.
If you have a limited knowledge of the application architecture, use TCM Expert to create the
workload apportionment weights portion of the WA model automatically.
To analyze your HP NonStop system configuration and application:
1. Identify major transactions as batch, OLTP, or query.
• A batch transaction is a workload that processes several transactions at once. Batch
transactions have the following characteristics: long job duration, low priority, significant
disk activity, little or no terminal interaction, and work within a closed system.
• An OLTP transaction is a method of processing transactions in which entered transactions
are immediately applied to the database. The information within the database is readily
available to all users through online screens and printed reports. They occur randomly,
often generated by a multitude of users. Generally, OLTP transactions require only modest
CPU and disk resource consumption per transaction.
• A query transaction is one that is modeled as a batch or online transaction, depending
on the CPU demand of the query transaction. Large demand queries are modeled as
batch. Small demand queries are modeled as OLTP.
2. Draw a process flow diagram for each major transaction.
3. Combine the process flow diagrams into one system-level flow diagram.
4. Design the model.
TCM and the Capacity Planning Process 21