Starting from XenApp/XenDesktop 7.x we have maintenance mode option on the Citrix app servers directly. We can turn on or off the maintenance mode on the servers which will only disable Citrix sessions on those servers. RDP connection will still work on the faulty app server. In XenApp 6.5 appcenter, we can only disable logons to the servers which will also disable RDP access to the server. Using load evaluator, we can come around this issue and disable only Citrix logins, while making sure that RDP still works.

We have to create a load evaluator and set CPU and memory as very less values so that the server reports full load to ZDC. Because of this, ZDC will not send any sessions on that server.

Follow below steps for the same:

1. Create load evaluator. Name it and select the check boxes for CPU Utilization, Memory Usage and Server User Load. Set CPU Utilization, Memory Usage settings as – Full load as 2 and No Load as 1, and server user load setting value as 1. Servers with basic usage, will have minimum cpu usage and memory usage. So we are setting 2% as peak usage for both cpu and memory. For server user count, even if 1 user/admin logs in, we are setting it as 100% load.

2. Next create a worker group, filter with “Farm Servers” under “Select source” option dropdown and add your faulty server to it.

3. Next create a computer policy in xenapp 6.5, and select “Server Settings” option to the left. Look for load evaluator name setting and select the load evaluator you’ve created in step 1. In the next step in that policy, apply this policy to worker group and select the worker group you’ve created in Step 2. Note: If you cannot use the browse option in selecting the worker group, type the name of the worker group directly.

4. Run gpupdate /force in the app server that you’ve added to load evaluator. If you don’t run this command, Citrix policy that you’ve created will not take effect immediately. You have to wait till the next policy update.

5. On ZDC server, run qfarm /load command. You should now see Server load as 10000 and load throttling load to off.

You can now connect to this server via RDP while citrix sessions are not routed to this server.

As we are creating a worker group, we can just add or remove servers to this worker group to remove them from hosting user sessions. If not, we can select OU option as well while applying the XenApp policy but we should add and remove servers to Windows AD users and computers every single time. Adding and removing from worker group is quick and easy.