I ran into an issue recently where three of five XenApp workers did not show up in the XenApp 6.5 farm via the AppCenter XenApp Console. I was unable to find anything online regarding the problem. This is how I resolved the issue.
XenApp 6.5 workers being provisioned from PVS 6.1.
XenApp workers on the same vDisk image.
The Citrix IMA service was also not running. When this happens, Citrix is not able to communicate with anything. Under System Event Views, there were several errors that occurred when starting the IMA service; one indicated that it was trying to join a zone that did not exist:
Seeing this, my first attempt to resolve the issue was to re-add the server to the farm. I used the following steps:
1. Run the XenApp Server Role Manager and choose edit configuration to re-add the server to the farm.
Note: The following steps were completed while the server was running the vDisk in standard mode. There is no need to change the vDisk to private.
2. Choose Prepare this server for imaging and provisioning.
3. Uncheck all provisioning options and select Next.
4. Select Apply.
5. Once the server is successfully configured, select Finish.
6. Reboot the server.
After following the above instructions, one XenApp server registered with the farm, but the other two did not. Both of those servers were still registering the same event viewer ID errors.
Here's how the issue can be resolved:
1. Using PVS 6.1 versioning technique, create a version of the base vDisk all XenApp workers are launching from.
2. Change the target device type of one of the machines, which is not registering, to maintenance mode. Boot using the maintenance mode vDisk.
3. Re-add the server to the farm following steps one through five above.
4. Repeat these steps until all servers are registered to the farm.
5. Once everything is running properly, discard the second version of vDisk.