SUMMARY
When using RLM floating licenses it is possible to point client machines on the network to multiple license servers. This is primarily used for failover licensing, where if the primary server goes offline a second server will start floating its licenses in its stead. This setup can also be used for load balancing purposes.
However, due to how RLM licensing works, clients pointed to multiple servers for load balancing purposes can result in duplicate licenses checkouts. This is where a client checks out two licenses to a single machine when launching additional instances of the same product on one workstation, e.g. Nuke.
MORE INFORMATION
When a user launches a product it will check each license server it has been pointed to in sequential order. In this example, a user launches Nuke on a client machine which has been pointed to two license servers using the environment variable:
foundry_LICENSE=4101@Server01;5053@Server02
Nuke will first try checking out a license from Server01 before moving on to Server02 if no licenses are available.
When an instance of a product is launched, it will always check for an available license. This is the case even if an instance of that product is already running and licensed. Usually when pointed to a single server, the client will see that it already has a license checked out, so it will not take another seat.
When pointing to two servers, the client may check out a license from Server02 first (if all Server01 licenses are in use at that moment). However, if a license becomes available on Server01 and a second instance of the product is launched, the client will take a second license from Server01, resulting in the machine occupying two licenses: one from Server 01, and one from Server 02.
This is then further exacerbated if using the environment variable RLM_PATH_RANDOMIZE on the client machines. This environment variable randomly selects one of the servers that the client is pointed to upon launch to check for a license. This means that you are more likely to point to a different server when launching a second instance of software and experience the duplicate check out.
WORKAROUND
To avoid this issue, we would suggest managing your licenses so that the servers and clients are separated. Instead of having client machines pointed to multiple license servers, we would suggest that they are only pointed to a singular server in order to avoid this duplicate license situation. For example:
Instead of having 50 licenses on Server01 and 50 on Server02 with 100 clients pointed to both machines, we would suggest having 50 clients pointed to Server01 and 50 to Server02.
FURTHER READING
Further information on installing and managing floating is available in the following articles:
Q100264: How to point a machine to your license server
Q100129: How do RLM failover servers work?
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