If you follow the LTSR builds of XenDesktop / XenApp then you probably upgraded from version 7.6 to 7.15. The upgrade steps are well described on Citrix eDocs or other blogs. But after upgrading there are some additional steps needed to take full advantage of the new features. This blog describes these additional steps.
XenDesktop 7.15 reintroduced the local host cache. This was a feature in XenApp 6.5, but in versions 7.x before 7.15 this was replaced by connection leasing. Connection leasing is a replay of previous session connections when the database is not available. With local host cache, the database is really cached again and the XenDesktop is fully functional. Delivery controllers automatically elect a master and communicate with each other about connections made. So it is recommended to switch from connection leasing to local host cache. The steps are really simple.
To determine whether Local Host Cache is enabled, open PowerShell on the delivery controller and enter the following commands:
The output will look like this (some lines are skipped):
BrokerServiceGroupUid : <guid>
ColorDepth : TwentyFourBit
ConfigLastChangeTime : 2/12/2018 1:56:26 PM
ConfigurationServiceGroupUid : <guid>
ConnectionLeasingEnabled : True
DefaultMinimumFunctionalLevel : L7_9
DesktopGroupIconUid : 1
DnsResolutionEnabled : False
IsSecondaryBroker : False
LocalHostCacheEnabled : False
If you see ConnectionLeasingEnabled: True and LocalHostCacheEnabled: False then you are in 7.6 mode. To switch on local host caching, use the following command:
Set-BrokerSite -LocalHostCacheEnabled $true -ConnectionLeasingEnabled $false
This cmdlet also disables the connection leasing feature. Do not enable both Local Host Cache and connection leasing. Check again with Get-BrokerSite is settings changed.
In version 7.13 Citrix introduced HDX Enlightened Data Transport. This is a new transport engine that uses HDX Adaptive Transport and the UDP protocol. It can automatically fallback to TCP when needed. This will give a better user experience. If you previously used legacy mode or FrameHawk, it is best to switch to EDT.
To use EDT, first upgrade all your VDAs to version 7.15. The configure the following policies. Please note that connections will temporary disconnect when settings change, so you better do this after business hours.
In user settings change the video codec policy to Use when preferred:
In computer settings set HDX Adaptive Transport to Preferred. This will use the UDP protocol when possible.
To use EDT on remote connections via NetScaler, DTLS must be enabled on the NS Gateway vServer. See http://docs.citrix.com/en-us/netscaler-gateway/11-1/hdx-enlightened-data-transport-support/configuring-netscaler-gateway.html