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Sluggish or Poor Virtual Machine Performance


There are various issues that can impact the performance of a Virtual Machine (VM) in the Cyber Range, making the user experience slower than normal. This article provides a slightly technical description of each issue, how to detect if one of the issues is the cause for your sluggish experience, and if it is the cause, how to address the issue.

Virtual Machine Delayed First Boot


When VMs on the Range are provisioned and started for the first time, each dedicated VM's underlying Virtual Hard Disk Drive (VHDD) is "instantly" cloned (by reference) from a saved VHDD image. Until the freshly provisioned system is fully "warmed up" (i.e. synchronized between the active VHDD device and the originating, read only, VHDD image), users will not be able to access their VMs. This process can take about 15-20 minutes depending on the environment. This warm-up process only impacts the first startup of a VM; subsequent startups will be much quicker.


To alleviate a majority of this wait time, the Cyber Range has implemented the Pool Model to provide pre-warmed VMs as often as possible. For more information, please see the article titled Cyber Range Pool Model. In cases where a pre-warmed VM may not be ready (e.g. setting the expected number of users too low for a large course), we recommend booting up all of your students' VMs at least 20 minutes before needed. This can be done by clicking "Start All" within the desired exercise environment. Please see Start All Exercises Feature for more information on this feature. This process only applies to first time access to a VM, and subsequent startups of the VM should only take about 45-60 seconds.

Custom Desktop Settings Causing Sluggishness


Instructors are free to customize exercise environments, including the ability to change the operating system's graphic settings (e.g. enable 2D/3D rendering effects, enable Compiz (on Linux), switch from XFCE to Gnome DEs, etc). If you are using a customized desktop environment like this, the additional CPU and memory resources needed for keeping such desktops properly refreshed can detract from the available resources for services and the OS' system scheduler. This can result in an overall slower VM session user experience. This can be seen by looking at the system load. If load levels are consistently high (or over 1-2 as seen from the Linux "uptime" command), or if you need to enable such multimedia rich settings, please contact support to request a VM environment with additional CPU and/or memory resources. Note, that adding CPU/memory resources to an existing class/exercise architecture after the fact may require the tearing down and recreation of related instructor and student environments.


This solution is related to desktop loads vs allocated resources. In short, the fix here is to either not run desktop intensive configurations (such as Compiz, 2D/3D effects, Gnome/KDE Desktop Environments, etc), or request higher CPU/memory settings for your classroom environments. Please see our article on CPU and memory settings of Range virtual machines for more information.

High Network Latency (Based on Location or ISP)


This is not a common issue, as the Cyber Range does not need a lot of bandwidth to deliver a crisp and snappy graphical environment. For example, some instructors have been able to host their class over a smartphone hotspot. However, what can impact perceived performance is high latency (or round trip packet time from client to the cloud and back to the client). High network latency can greatly impact the user experience, especially on graphical (non-console/ssh) sessions. As such, we recommend against high-latency connection technologies such as connecting to the Range over VPN (encrypted Virtual Private Network) connections, satellite ISPs, or congested/shared WiFi (e.g. where clients watching YouTube or Netflix can impose choppy latency issues).

How to Diagnose

You can test your "ping time" to the front end of the Cyber Range by opening a terminal or CMD text window and typing "ping" on your local PC. Any ping time of under 50ms should provide a very usable client experience. A ping time from 50-100ms is usable. But a ping time over over 100-200ms will incur noticeable sluggish or "choppy" client experience.


If you are on a high latency network, try reconnecting from an environment with better connectivity (using the ping test as a rough metric).

Have a Question? Contact Support


Students: Please reach out to your Instructor who can submit a ticket to our Support Team on your behalf.

We're here to help you. If you still have questions after reviewing the information above, please feel free to submit a ticket with our Support Team and we'll get back to you as soon as possible.