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Stop Wasting Time: How Time Settings Affect VDI Performance Tests

Stop Wasting Time: How Time Settings Affect VDI Performance Tests

Time zones are settings that are configured once by system administrators and are never looked at again. Why would you even bother to take a look at it again when everything works? That’s a very good question, but based on our own experience with customers, we know that the time settings are not always configured correctly. Not only can this affect your entire virtualized desktop environment, especially security authentication suffers from it, but it can also ruin your Login VSI test results. To avoid wasting your time, we will discuss time settings in this blog.

“Time you enjoy wasting, was not wasted.”

-John Lennon

Time for Windows

When there is a difference between time zones on the domain controller and the clients you get an error message when logging in to the client with a domain user. The error is, as always, very descriptive and gives you the exact reason why you are unable to login….

The error message states:

stop wasting time how time settings affect vdi performance tests windows login error message

The security database on the server does not have a computer account for this workstation trust relationship.

Like I said, it’s very descriptive. Anyway it’s a pain since the best way to solve this issue is by removing it from the domain, configuring the time correctly and reconfiguring the domain connection.

Time for testing

The impact on results for Login VSI is pretty big as well. Strangely enough we sometimes come across results that show a few hours difference in time zones of different clients. Which is strange because Windows is always so nitpicky when it comes to correct time zones within the domains (see example above).

The biggest impact that we see is that customers come to us stating that they have a large amount of stuck sessions. But when we look at the logged off sessions we see that at least 90-100% had reported they logged off.

stop wasting time how time settings affect vdi performance tests logged off sessions different time zone

What was the cause? It was the different time settings on the different targets. Apparently a few hosts were configured to run in a completely different time zone.

Because Login VSI looks at the date/time stamp, it figures that a large portion of results are done before or after the test and this means that Login VSI also considers these sessions as stuck. Which results in strange graphs and users calling our support department.

Little time

Even a small difference of 5 minutes can skew a test result, simply because the measurement was not where it should be. This can be the difference of stuck sessions or successful sessions within the Login VS Analyzer. To gain insight in the maximum capacity of your VDI environment, the number of successful sessions is pretty important…

Taking your time for time

A lot of, if not all, virtual machines sync their time zones with the host and the Domain Controller. The physical host in turn syncs its time with the Bios by default. Of course using an NTP setting will bypass a lot of issues but the default settings can still be an annoyance.

stop wasting time how time settings affect vdi performance tests ntp time settings

The fastest way of fixing it is to make sure that the bios of all of the physical hosts are set at the same. This way there can be no issue regarding the time settings and their default is always correct.

stop wasting time how time settings affect vdi performance tests bios time settings

Our best practice is to disable time syncing with the host (on all client VM’s) and setting up an NTP in the environment.

I hope this blog reaches you on time, before something untimely happens.

About the author

Tom Willemsen is a Support Engineer at Login VSI and helps customers and gives advice about testing with Login VSI. He loves to travel, read about history, and see different cultures. In his free time, Tom likes to game and watch movies.


Tags: Login VSI, Load Testing, Best Practices, Support

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Eddy Zeehuisen - Gemeente Utrecht

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Eddy Zeehuisen, Program Manager U-Cloud at Gemeente Utrecht (Municipality of Utrecht, The Netherlands)


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Shai Maskit, Director of Product & Solutions at Kaminario

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