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Step 6: Perform Constant Load Pattern Tests to Verify Maximum Sustainable Throughput

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When load testing a BizTalk Server solution using Visual Studio 2010, a constant load pattern test should be performed once the approximate Maximum Sustainable Throughput (MST) of the solution is determined as described in Step 5: Perform Step Load Pattern Tests to Determine Maximum Sustainable Throughput. This should be done to confirm that the MST is in fact sustainable over time and also so as to create a baseline load test moving forward to evaluate the effects of any performance tuning applied to the BizTalk Server application or environment.

Create and run a Constant Load Pattern Test

The easiest way to create a Constant Load Pattern test that uses the same Test Mix, Counter Sets, and Counter Set Mappings used by the Step Load Pattern test is to simply save the Step Load Pattern test “BTS_Messaging_Step.loadtest” as “BTS_Messaging_Constant.loadtest” and then make some changes to “BTS_Messaging_Constant.loadtest”. Follow these steps to create a Constant Load Pattern test that is based upon the existing Step Load Pattern test:

  1. Open BTS_Messaging_Step.loadtest if it is not already open.

  2. Click File and select Save LoadTests\BTS_Messaging_Step.loadtest As.

  3. In the Save File As dialog box, next to File name, enter C:\Projects\LoadTest\BTSLoad\LoadTests\BTS_Messaging_Constant.loadtest and then click Save.

  4. In the Load Test Editor, rename the scenario BTS_Messaging_Step to BTS_Messaging_Constant. The scenario name is displayed directly under the Scenarios folder.

  5. Leave the values for Test Mix and Network Mix unchanged but click to select Step Load Pattern.

  6. Right-click Step Load Pattern and select Properties.

  7. In the Properties section, under Load Pattern click the dropdown list next to Pattern and change the Pattern from Step to Constant.

  8. In the Properties section, under Parameters, change the value for Constant User Count to a value slightly less than the number of users at which the Step Load Pattern test was becoming unsustainable (i.e. the value for the BizTalk:Messaging\Documents received per/Sec began to consistently exceed the value for BizTalk:Messaging\Documents processed/Sec and the value of the BizTalk:Message Box:General Counters\Spool Size began to increase unbounded).

  9. Under the Run Settings folder, right-click Run Setting1 [Active] and select Properties.

  10. Scroll down the list of properties to the Timing section and enter a value for Run Duration of at least 10 minutes (00:10:00) and verify that the value for Sample Rate is still set to 5 seconds (00:00:05).

  11. Start the load test by right-clicking the test name (e.g. BTS_Messaging_Constant) and then click the Run Test menu option.