We have seen an issue in xenapp 7.6 where some of the vms are shutdown automatically after weekend reboot. After lot of research on the delivery controller, we have identified that Delivery controller is sending the shutdown command to some of the vms(random vms every week) and esx is shutting down the vms. So we have decided to turn off power management completely in our xenapp 7.6 environment.

Here are the steps to set your power management to max for all delivery groups.

To power on all the VDIs in all delivery groups 24/7 use below commands.

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Add-PSSnapin *Citrix*
Set-BrokerDesktopGroup -Name * -AutomaticPowerOnForAssigned $True
Set-BrokerDesktopGroup -Name * -AutomaticPowerOnForAssignedDuringPeak $True
Set-BrokerDesktopGroup -Name * -OffPeakBufferSizePercent 100
Set-BrokerDesktopGroup -Name * -PeakBufferSizePercent 100
Set-BrokerDesktopGroup -Name * -ShutdownDesktopsAfterUse $False

Note: Need to execute the above commands in delivery controller.

Above commands would let all your VDAs be in power on state, even after users logoff. Reboot schedule may be difficult when setting up delivery groups like this.

If you are working on a test environment or dev, where you need your VDA (or VDI) to be turned off until you click on the VDI icon in your citrix portal, you can set buffer VDI size to zero as shown below. With below commands all your VDIs will be powered off and they will be powered on only when you click on the VDI icon in your citrix portal.

To disable power management completely,  use:

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Add-PSSnapin *Citrix*
Set-BrokerDesktopGroup -Name * -AutomaticPowerOnForAssigned $False
Set-BrokerDesktopGroup -Name * -AutomaticPowerOnForAssignedDuringPeak $False
Set-BrokerDesktopGroup -Name * -OffPeakBufferSizePercent 0
Set-BrokerDesktopGroup -Name * -PeakBufferSizePercent 0
Set-BrokerDesktopGroup -Name * -ShutdownDesktopsAfterUse $True

Note: This would take a while for the session to start as VDIs are in powered off state, you have to wait till they are powered on and your session is logged in.

To power off VDIs after users logoff, and power on only when they click on the VDI in storefront or netscaler gateway url, use below commands.

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Add-PSSnapin *Citrix*
Set-BrokerDesktopGroup -Name * -AutomaticPowerOnForAssigned $False
Set-BrokerDesktopGroup -Name * -ShutdownDesktopsAfterUse $True

You may leave peak and offpeak buffer size percent at 100% on it. If you have static VDIs, peak size and off peak buffer size percentages are not important. You should also create a gpo to set idle time and disconnected time as per your organization needs. So, idle session moves to disconnected state, disconnected session will be logged off after configured time. Logged off VDI will be powered down.

Benefits of this approach:

• Setting up delivery groups like this will also work as reboot cycle for the VDIs. When user logs off the VDI, it will be powered off. When users click on the VDI in storefront or netscaler gateway, it will be powered on. So, this works as reboot.
• If your VDIs are up and running all the time, users leave their apps like outlook, vscode, studio, git consoles, sql studio etc running in the VDI when they leave for the day. So, even though users are not using them, they will consume CPU, memory resouces on your hypervisor hosts. These settings will work as reboot cycle and also will reduce load on your hypervisor.

Only issue with this approach is, users have to wait till VDI is powered on and registered. Logon time may take a while. You have to decide between your infrastructure to be green, or user’s experience.