Stress Testing

Stress testing lets you find out how your system behaves under heavy loads and how increased transaction volume affects response time. System programmers can use this information to tune the system. Capacity planners can use it to determine when and how to expand system capability to meet projected growth estimates. Because CA Verify for VTAM uses virtual terminals instead of real terminals, you can simulate system activity without tying up valuable system resources.

Follow these steps:

Create one or more multiple terminal test streams by logging many terminals at once. For example, you may want to log all the terminals in a particular department or all the terminals in a region.
Create a large-volume test stream by merging the test stream with itself or by merging several test streams. The screens from one test stream are interspersed among the screens from a second test stream.
Run the merged test stream either online or as a batch job.
- When CA Verify for VTAM runs in batch, it brings up a CICS region in which it is the only user. Because there is no resource contention, transactions execute under optimal conditions. Such information may be valuable for optimization or tuning.
- To simulate increased stress, reduce the operator think time. For example, you can request that input screens be sent to the application twice as quickly as the operators originally sent them. You can even specify no operator think time. Reducing think time is a good way to simulate a stress test even with moderate transaction activity.
- Because you're not concerned with program changes, instruct CA Verify for VTAM not to compare the original and current screens. Of course, if you logged only input screens, no comparison will take place.

Note: To test an incremental increase in transaction volume, run a test stream containing the additional volume during peak periods.