Having taught many XA & XD course I often mention that having a HA Licence Server isn’t that necessary however when we start working on more large and complex environments, the requirement to have a HA Citrix license server becomes more relevant. We are starting to get more options now, however, Citrix recommends MS Clustering. Microsoft clustering is hard work and cumbersome so the thought of two standalone servers with a Netscaler loadbalancer should work. With license service running on Windows, you have to activate licenses twice, because the licenses are tied to the hostname. Now we have the Citrix License Server VPX running a Linux appliance, which allows us to use the same hostname on two appliances, but with different IPs!. No need to have duplicate license files. Cool eh?
All you have to do is to create a load balanced vServer on your NetScaler, point to the license server ports on both appliances, and then add weight to one appliance to be in compliance with license count.
The other option is to create a VIP pointing to a single host, then create a back up VIP pointing to the secondary license server and bind the back up VIP to your primary. This will ensure all traffic goes to a single license server, and fail over only if the primary license server fails or you need to perform some sort of maintenance.
XenApp Farm points to VIP: 10.10.68.10
VIP on NetScaler: 10.10.68.10
License Server VPX 1 (hostname ctxlic): 10.10.68.11
License Server VPX 2 (hostname ctxlic): 10.10.68.12
Weight set to 1 on VPX 2
Weight set to 2 on VPX 1
Set TCP monitor for this load balancer to ensure it is monitoring TCP 27000 traffic. Then you use the load balancer VIP as the License server in XenApp/XenDesktop/AG, etc configurations and you are done!
Thanks to Daniel Ruiz for the original post reference this idea.