Understanding LoadRunner Virtual User Days (VUDs)

Micro Focus, Tech TipsJDS10 Comments

Previously we wrote about the different types of LoadRunner licenses available. There were still a lot of questions about VUDs, so this Tech Tip aims to help people better understand this virtual user license type.

What is a VUD

A VUD is a Virtual User Day. While a virtual user day is considered a 24 hour user, 24 hours is the maximum amount of time that a Virtual User is valid.

VUDs provide a cost effective method of boosting the number of virtual users available in a performance test or set of performance tests run over period of time. In addition to the license for VUDs, a license for the LoadRunner Controller or Performance Center must be in place.

How to order VUDs

VUDs are available to any LoadRunner or Performance Center installation. Licenses can be ordered through HP or an HP Software partner like JDS Australia. The license key will be issued by HP in the same way as the other LoadRunner license types.

Configuring VUDs

Virtual User Days have an expiration time. This time can be set through HP support. Set the time for a time an hour or two after the performance tester first arrives at the office. Really, the start time should be set to a time when you are not running a test. If a performance test has been run involving VUDs, the LoadRunner Controller should be shutdown before the start/expiration time occurs.

VUDs can be used in conjunction with permanent/perpetual virtual users. There is no conflict between the two licenses. VUDs will only be expended after the all of the eligible permanent virtual users have been expended.
VUDs are activated by running a virtual user. The effect of running a virtual user is that the virtual user is decremented from the license.

Spending VUDs

Running a test with a number of VUs less than or equal to the amount on a permanent license will not result in an expenditure of any VUDs.

Poor Expenditures of VUDs

Running a test which starts before the expiration time and ends following the expiration time, results in a double charge of VUDs.

When the Controller is open, even if the test run has completed, the VUs that have been allocated to the current test will be decremented from the license at the roll over time. Therefore it is unwise to run tests on a Friday night, unless you are planning on getting to the office to turn off the controller before the start time occurs.

Wise Expenditures of VUDs

Run multiple tests in a day. Make use of the VUDs in more than one test in a day. If possible run your first test using VUDs. Analyze the results of the test, recommend and implement changes to the system under test and rerun the same test. This provides a multiple uses of the same VUDs, while testing configuration changes of the system under test. Make certain that the test scenario is closed before the expiration/start time for the VUDs ticks over.
Analysis is more important than rerunning tests with VU. Accurate identification of issues within the system returns more value than rerunning tests to confirm results. When writing the test plan take into account the VUDs and try to maximize the value of each, by stacking tests using similar quantities of VUDs which accomplish different goals.

Examples

The following examples are designed to test your knowledge of VUDs.

Scenario 1
  • Permanent Web VUs available: 200
  • Web VUDs available: 1000
  • VUD expiration/start time: 11:00

300 VU Endurance Run: Kick off test at 17:00, watch rampup and head home. Test completes at 05:00 the next day. Enter the office at 09:00. Review VUser errors through the Controller for an hour. Shutdown the controller or reset the scenario before 1059:59.

  • VUDs expended: 100
  • VUDs remaining: 900
Scenario 2
  • Permanent Web VUs available: 200
  • Web VUDs available: 1000
  • VUD expiration/start time: 11:00

300 VU Endurance Run: Kick off test at 17:00, watch rampup and head home. Test completes at 11:00 the next day. Enter the office at 09:00. Review VUser errors through the Controller for an hour. Shutdown the controller or reset the scenario after 11:00.

  • VUDs expended: 200 – although 100 remain for the rest of the day.
  • VUDs remaining: 800
Scenario 3
  • Permanent Web VUs available: 200
  • Web VUDs available: 1000
  • VUD expiration/start time: 11:00

700 VU Peak Run: Kick off test at 11:30, watch rampup and analysis of the run while running. Test completes at 14:30. Controller is shutdown or reset following the scenario completion.

  • VUDs expended: 500
  • VUDs remaining: 500
Scenario 4
  • Permanent Web VUs available: 200
  • Web VUDs available: 1000
  • VUD expiration/start time: 11:00

700 VU Peak Run: Kick off test at 11:30, watch rampup and analysis of the run while running. Test completes at 14:30. Controller is shutdown or reset following the scenario completion.
700 VU Peak Run: Make changes to the application. Kick off test at 15:00, watch rampup and analysis of the run while running. Test completes at 18:30. Controller is shutdown or reset prior to 11:00 the next day the scenario completion.

  • VUDs expended: 500
  • VUDs remaining: 500
Scenario 5
  • Permanent Web VUs available: 200
  • Web VUDs available: 1000
  • VUD expiration/start time: 11:00

700 VU Peak Run: Kick off test at 11:30, watch rampup and analysis of the run while running. Test completes at 14:30. Controller is shutdown or reset following the scenario completion.

700 VU Peak Run: Make changes to the application. Kick off test at 15:00, watch rampup and analysis of the run while running. Test completes at 18:30. Controller is not shutdown or reset prior to 11:00 the next day the scenario completion.

  • VUDs expended: 1000
  • VUDs remaining: 0 - although 500 remain available for the remainder of the day.

Please leave a comment if you still have questions about VUDs.

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