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Floating License Three-server Redundancy Cluster

SpinFire Ultimate V11 - Three-server redundancy cluster (Failover)

The Flexnet constellation is consisted of Three license servers, all inter-connected by TCP/IP. These machines are adequately named “Primary”, “Secondary” & “Tertiary”. It is ideal if you have a set of three license servers available and wish to implement failover protection for your license server.

When at least two of the three license servers are running and communicating, the system will serve the license. The primary license server will act as the master and serve the license.

Triad Redundant Server Constellation

If the master failed, the secondary server will become the master and serves the license, providing that the tertiary server is up and running. 

Triad Redundant Server Backup Failover


Any one of the two first machines (Primary or Secondary) may be defined as the “Master”. All licenses are served by this Master machine.

The three FlexLM license servers are started up separately according to their order (primary, secondary, and then tertiary) and the Master role is set according to this order or according to a designated flag: “PRIMARY_IS_MASTER” in license file (optional).

The FlexLM license Servers inter-communicate by a “Heartbeat” messages over TCP/IP, using the same port number. A machine which fails to receive a response to its sent Heartbeats turns down the vendor daemon and can not serve licenses.

When the Master server (Primary or Secondary) fails, the Master role is passed to the other (Secondary or Primary) server. The new Master assumes the license management role for SpinFire.

We need receive the HostID and Host name of the machines (“Primary”, “Secondary” & “Tertiary”) that should be used as a three-server redundancy failover.

Some changes (optional) may need to be done in the license file according to this new information, such as the PRIMARY_IS_MASTER value, the communication port number and the HEARTBEAT_INTERVAL which is effectively the timeout for license servers to be knocked out of the triad.

The format of the SERVER line is:



The port number that the license server uses to listen for communication.

Unlike single license servers, each SERVER line must include a port number on a server triade.

This can be any number between 1024 and 64000 that is not used by another process running on the system. Default is mostly port 27000. This value can be changed after the license file has been signed.


Used with license servers configured for three-server redundancy to indicate how master control is transferred between the primary and secondary servers.

This parameter is optional and is placed on the first SERVER line in the license file.

If this is set and the primary server goes down, when the primary server comes back up again, it will always become the master.

If this is not set and the primary server goes down, the secondary server becomes the master and remains the master even when the primary server comes back up. The primary can only become the master again when the secondary license server fails.


Used with license servers configured for three-server redundancy to indicate how long a license server waits to receive a heartbeat from another license server in the triad before shutting itself down.

Valid timeout value is 0-120. If not specified, the default value for seconds is 20, equating to an actual timeout value of 79 seconds. Valid values for the seconds value are 0–30

This parameter is optional and is placed on the first SERVER line in the license file.

Using Options File Keywords

None of the keywords in the options file affect three-server redundancy.

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