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.”
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:
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.
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.
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.
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.
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.
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About the company Login VSI
The company Login VSI provides end-user performance insights for virtualized desktop and server-based computing environments. Enterprise IT departments use flagship product Login VSI (for load testing) and Login PI (for continuity testing) in all phases of their virtual desktop deployment—from planning to deployment to change management—to build and safeguard a good performance, a high availability, and (as a result) a good and consistent end-user experience. For more information about Login VSI or for a free test license contact us.