login vsi company logo login vsi company logo 250x40

VDI Load Testing: When do I need an extra VSIshare?

VDI Load Testing: When do I need an extra VSIshare?

Why do people perform load tests of their virtualized desktop environment? Most likely to get more insight in the performance and maximum capacity of their environment. In order for Login VSI to give you these test results we need data--lots of data. That’s why during a large-scale Login VSI test, logfiles are continuously sent to the VSIshare and sessions are also doing read actions on the files that are located in the VSIshare. This means that a lot of data is written to the VSIshare and sometimes your VSIshare can get overloaded. This can have a negative impact on your test because of 1. loss of test data and 2. timeouts during copy actions.

How to see if this happened during a test

The best way to find out if this is happening during your tests is to open the Analyzer and look at the VSImax v4 Scatter tab. The data is by default presented with response times in milliseconds on the Y-axis and the amount of sessions on the X-axis.

To see if the VSIshare is the bottleneck we should sort the scatter chart by time. This can be done in the dropdown menu underneath the chart. Now that we have sorted the chart by time, the Y-axis is still showing the response times in milliseconds but the X-axis will show the time when the data was collected.

The chart should show a steady line of results just like the graph that is sorted by the amount of active sessions. A lot of gaps between the data (like the screenshot below), indicates that the results can’t be written to the VSIshare and your VSIshare was overloaded during the test.

vdi load testing when do i need an extra vsishare vsimax v4 scatter chart

A lot of gaps in the VSImax scatter chart indicates that your VSIshare was overloaded during the test

How to solve the issue

Extra VSIshare

Issues are there to be solved. One way to solve this issue is by decreasing the load on the VSIshare by moving the Data Servers and Webservers to a second VSIshare. First create a new VSIshare on a different server and copy the _VSI_Content and _VSI_Websites folder into the new share. Now that the new share is created we need to go to the Data Servers tab in the Login VSI Management Console and adjust it with a double left click on the UNC Path. Besides the Data Servers we will also need to change the UNC path for Web Servers, this can be done with a double left click on the UNC path at the Web Servers tab in the Management Console.

The Data Servers and Web Servers are now hosted on a different machine. This will reduce the load on the VSIshare and gives you the opportunity to re-run the test without the Login VSI share being overloaded.

RAM disk

Another easy solution is a RAM disk. Often the I/O load on the server where the VSIshare is hosted seems to be the bottleneck. Several tools give you the possibility to create a RAM disk. This will create a disk located on your memory. Move the VSIshare to the RAM disk and your VSIshare will get an IOPS boost.


A large-scale test generates lots of data, this data can cause the VSIshare to become overloaded. A lot of gaps in the VSImax scatter chart can help you to locate this issue. To solve this we can create a second VSIshare for the Data Servers and Web Servers OR create a RAM disk and move the VSIshare to get an IOPS boost.

About the author

Jasper Geelen (@jaspergeelen) has a background in ICT and joined Login VSI as a pre-sales engineer in 2015. He loves drinking a lot of coffee (some might call him an addict). In his spare time, Jasper enjoys a beer and he is part of a football / soccer team. He also coaches a team of younger football players.

Tags: How-to, Login VSI, Load Testing, Best Practices, VSImax, Support

What our customers are saying

Michael Bernas - Workers' Compensation Board Alberta

“We've used Login VSI for the past 3 years as part of our Disaster Recovery Exercise. It's not only helped us in validating the functionality of our Citrix XenApp farm, but it's also been an invaluable tool in proving the number of concurrent connections into the environments. It’s allowed us to take our theoretical numbers and put actual real life data behind them.”

Michael Bernas, Workers' Compensation Board of Alberta

Sajad Shah - Cancer Research

"Login VSI has empowered us to make more informed decisions on releasing a new vDisk which we now do on a monthly basis. We have found that Login VSI tests can also flag other issues in our environment that may not be picked up by our standard User Testing which allows us to either make the appropriate changes to the vDisk or workload script adjustments to run successful tests. This has given us peace of mind and allows us to release VDI’s with confidence."

Sajad Shah, Senior Technical Analyst at Cancer Research UK

Tony Reynolds - 23Technology

"As a cloud and virtualisation consultancy, 23Technology use Login VSI to prove the scalability of our paper designs for our customers. It has become an important part of our assurance process. In one instance, it helped us to successfully complete a project by showing that, with correctly configured anti-virus, the designed solution scaled to meet our client’s needs."

Tony Reynolds, Technical Director at 23Technology

Login VSI, Inc.

300 Tradecenter

Suite 3460
Woburn, MA 01801

Phone: +1 844 828 3693

Login VSI B.V.

De Entree 85
1101 BH Amsterdam
The Netherlands

Phone: +31 20 705 1200