XenApp 6.5 Worker Servers, why and how to use them.
With XenApp 6.5 there are new features like Session Lingering, Session Pre-Launch, Multi-Stream ICA. The feature I get the most questions in class are about Session-host mode only or “Worker” servers. Questions like: why should it be used, what are the advantages and disadvantages of using workers.
Controller vs. Worker:
The difference between a Controller and Workers are the installed roles. A Worker is unable to participate in an election. The reason is that het has no data collector roll installed. It’s also of no use to use a Worker as XML broker. Because it has no XML service installed.
Let’s start how to configure a Worker:
After the installation of XenApp 6.5 you need to start the Citrix XenApp Server Role Manager. Click on Configure to start configuring you XenApp 6.5 Server. Start configuring until you reach the specify the advanced server settings screen.
Click Enable Session-host mode only and your XenApp Server will be a Worker. Finish the reboot and you have a Worker in your XenApp Server Farm.
So why should we use an Worker?
The main en most importer reason to us a Worker is bandwidth and the second reason is the startup time of you IMA service. Because the server is unable to become a Data Collector, there is no need to download all the information from Data Store. The Local Host Cache (LHC) will be much smaller. Less replication across WAN or LAN between the Data Store en XenApp Servers.
The other reason is to solve a problem I have discussed in a previous post: Do you know your XenApp Zone Data Collector? By only installing the Controller on your Most Preferred and Preferred Data Collectors you don’t have to think about the highest IMA services.
Why shouldn’t we use a Worker:
In an XenApp Farm with only Controllers every XenApp Server is a potential Data Collector. Let’s say you build a XenApp Farm with 2 Controllers. Both servers crash or are unavailable . Then new users are unable to log on and disconnected sessions cannot be reconnected. So make sure you have enough Controllers in your Farm.
Another problem is that you are unable to use management tools connected to the XenApp Server. When using AppCenter to run against a Worker you will receive an error.
So if you are planning a Management Server, it has to be a Controller.
For those who have worked with XenDesktop 4 and then switched to XenDesktop 5 have seen a major change. Will the next step with XenApp be similar from XenDesktop 4 to XenDesktop 5? Will Citrix lose the IMA service for XenApp as they did with XenDesktop? In my case it’s seems a small step from a Controller to a DDC.