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Citrix released XenDesktop/XenApp 7.12 and with it some features that have been around for a very long time in the IMA architecture, that is up to XenApp 6.5. If you have worked long enough with XenApp 6.5 or before, you might be thrilled to know those features are back, or at least something close to it.

Here are some things (not all) that I picked from the release that I found worth mentioning.


What's new with XenDesktop 7.12

High availability using Local Host Cache (LHC)
The LHC is back! From day one of XenDesktop 7, Citrix CTPs and others were getting after Citrix and the missing LHC functionality. Citrix later came out with the "Connection Lease" and was more of something that looked like a poor kid compared to the LHC. Now, this is the first "try" of the LHC within XenDesktop 7 implemented as High Availability Service. BTW, Citrix is using the 'NT Service' accounts that have already caused issues in the past (see VDA upgrade issues). I'm writing TRY because of the known issues that you will find below, pointing out the problems with HA Windows service.

In a nutshell, how it works:  Another Windows service, the Config Synchronizer, syncs continuously data (only when changed) to HA service that stores the data in the LHC; local DB. If the site DB fails, then the principal broker sets the secondary broker active to take over to serve until the site DB is back online.


Tag restrictions with Application Groups and Desktops
This sounds like an interesting way to get something back that many old XenApp Admins were looking for from the start of XenDesktop 7. How can I publish a single app or desktop from one machine out of a Delivery Group? So far you would need to create an extra Delivery Group and machine catalog and then move the machine in question. Instead of that, you can now set tag restrictions that will limit a delivery group or machines in a machine catalog. Let's see how practical that is in reality. Here is the Citrix description:

"Using a tag restriction enables you to use your existing machines for more than one publishing task, saving the costs associated with deploying and managing additional machines. Using a tag restriction can be thought of as subdividing (or partitioning) the machines in a Delivery Group. You can also use a tag restriction to help isolate and troubleshoot a subset of machines in a Delivery Group."

HDX Enlightened Data Transport (for evaluation only)
This is another try out for customers, I guess, to get some real feedback if it's going in the right direction. The new HDX data transport layer is designed for challenging long-haul WAN and Internet connections. This new transport layer uses UDP to improve data throughput for all ICA virtual channels to include Thinwire display remoting, client drive mapping, printing, multimedia redirection, and others. HDX Enlightened Data Transport should only be enabled for evaluation purposes and done with a new policy setting but a fallback to TCP is part of the release. The HDX feature requires Receiver for Windows 4.6 or Receiver for MAC 13.5

NetScaler Gateway High Availability (HA) is supported with Framehawk
Framehawk is slowly gaining attention by customers and it's overtime to make it available through a pair of Netscalers that are working in High Availability.


Multiple restart schedules for machines in Delivery Groups
Finally, you don't have to restart the whole Delivery Group at once, and especially in bigger environments where it's much needed. Now you can create multiple restart schedules for a Delivery Group. A question I have is why wasn't that part of the initial release? Citrix claims to have the 1.000 server farm for testing purposes, and that they never have to restart their server; do they use something else?


Increased historical data availability in Enterprise edition
Some overdue love for Enterprise customers, giving them a longer time of historical data, can be viewed in Director and now up to 31 days.



XenApp and XenDesktop 7.12 release contains the following issues

NOTE: This is just a selection of issues I picked!

  • Upgrading a Delivery Controller might fail with the error code: XenDesktopSetup: Process completed with
    error 1603. Additional messages indicate that Broker_Service_x64.msi failed to install. If this occurs, force
    stop the Citrix Broker Service (or terminate that service if a stop does not work), and then retry the Controller

  • On Windows 7 machines, the VDAWorkstationCoreSetup VDA installer creates system restore points for
    every ICAWS driver. This can add up to 15 minutes to the VDA installation. As a workaround, disable the
    Windows System Restore feature (Control Panel > System > System protection > Configure > Restore
    settings, select "Turn off system protection").

  • On Windows 7, the VDAWorkstationCoreSetup VDA installer might fail with error ID XDMI:DD9A87F1
    (installing the IcaWS_x86.msi file). Workaround: Run the VDA cleanup tool (CTX209255) and then retry the

  • When using the full-product installer's graphical interface to install a VDA on a physical machine, the
    Features page option to enable the Framehawk port is not available. Workaround: After installing the VDA,
    run the command
    "[Install Directory]\ICAConfigTool\IcaConfigConsole.exe /ExecutionMode:configure

  • During logon or logoff on a Windows 10 or Windows Server 2016 machine, the operation may pause and
    appear to be hung. Click in the session window to resume the operation.

  • When Local Host Cache is enabled, users with desktop connections might be unable to reconnect to the
    desktop during an outage. If this occurs, restart the Citrix High Availability Service.


Notes to LTSR after the NEXT Long Term Service Release (LTSR)

The following platforms will not be supported after the next LTSR:

  • VDAs on Windows 8.1 and earlier Windows desktop releases.
  • VDAs on Windows Server 2008 R2 and earlier Windows server releases.
  • XenDesktop 5.6 used on Windows XP

The following features will not be supported after the next LTSR:

  • Connection leasing (Replaced by LHC)
  • Legacy Thinwire mode (that was for Operating Systems that are not supported anymore)
  • Desktop Composition Redirection (DCR)
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