VSImax or EUX scores Do Not Yield Expected Results

Overview

In some cases, VSImax or EUX scores are not successful or may not yield the expected results. If this happens, we recommend checking the following:

Test with fewer users: Does the result improve with fewer users?
Ensure maximum power settings: Verify that all components are configured for maximum power.
- Hypervisor
- Virtual Machine (VM)
- Windows OS
Run optimization scripts: Ensure you've used optimization tools like VMware OSOT or Citrix Optimizer.

VSImax Could Not Be Provided Because the EUX Score Could Not Be Calculated or Is Not Valid

VSImax is the point where your total number of active sessions causes overall server performance to drop enough that the responsiveness of the individual sessions within that server is impacted. Load Tests are designed to help you determine that point, by scheduling a large number of sessions to log in over time and measuring how those sessions respond as more of them come online.

VSImax is calculated during a Load Test by determining the point where the 5-minute running average of EUX scores drops below the configured CapacityTrigger, which is 5.5 by default. That transition must happen while sessions are still logging in, and you must have a minimum number of EUX measurements returned.

If those requirements cannot be satisfied, we will be unable to calculate VSImax, and the Test results will show a warning like this:

To be able to calculate VSIMax:

Your total login window must exceed 5 minutes
Your login window must have at least 5 EUX measurements across all sessions
Your aggregated EUX score across all sessions must start above 5.5 (called CapacityTrigger)
Your aggregated EUX score across all sessions must cross below 5.5 during the login window

If your EUX score is always below the threshold, or your login window is not long enough, then you will get the error.

If your EUX score is always above the threshold, then we still can’t calculate the VSIMax. However, we know it will be higher than your current maximum number of sessions. Your Test results will show your VSIMax as “>{session count}” and the Test details will include this banner:

Practically speaking, you need multiple concurrent sessions running and a long enough login window that your multiple sessions can give us enough data to make a statistical analysis. Any individual session will only produce an EUX measurement every 3 minutes (or more).

It is possible to globally change the CapacityTrigger to another number, or a relative drop in performance from the baseline. For more information, see Baseline and Steady State EUX Scores. If you think you need to adjust your global baseline, contact Login VSI Support at support@loginvsi.com.