Key points about licenses in a cluster:
- Within a cluster, user licenses are shared among all nodes.
- Licenses are additive in cluster. The total user count would be sum of all nodes in the cluster.
- Install licenses equally on each node in the cluster
- Careful consideration should be taken when removing a node from a cluster. Removing a node will impact the total number of users.
Reason for installing licenses equally in a cluster:
The reason is to prevent loss of user count during node failure. A node can only borrow up to two times (2x) the total number of licenses installed on the device locally for a 10 day grace period. After 10 day period, the user count will revert to the total number of license installed locally.
If the licenses are evenly distributed in the cluster, the user count will remain the same regardless which node fails. If the license are unevenly distributed in the cluster, the user count will be different depending on which node fails (Refer to Scenario A and B for examples).
- Node_108 = 35 user license
- Node_109 = 100 user license
When clustered, the total number of users is 135 (35 + 100 = 135).
If Node_109 goes down, the total number of licenses would be 70 users. ( 35 X 2 = 70).
The maximum number of users will be 70 for the 10 day grace period. After the grace period expires, the user count will drop to 35 users.
If Node_108 goes down, the total number of licenses would be 135 users (100 + 35 = 135).
The maximum number of users will be 135 user for the 10 day grace period. After the grace period expires, the user count will drop to 100 users.
Why is the calculation different?
In this scenario, the device can only borrow up to the total number of user licenses in the cluster. This means instead of (100 x 2 = 200), it will only (100 + 35 = 135).
How License count is impacted when removing a node from a cluster?
If a node is removed from an existing cluster, this will decrease the total user count. For example:
- Node A = 100
- Node B = 100
- Node C = 100
The total user count would be 300 (100 + 100 + 100). If Node C is removed from the cluster, this will drop the total number to 200 (100 + 100) as Node C is no longer part of the cluster.
Recommendation for node replacement:
The general recommendation is to never delete a node from a cluster unless the device needs to be changed to a standalone device. If a node needs to be replaced in the existing cluster, the following steps are recommended:Note:
The following steps should be performed during a maintenance window. When the replacement device joins the cluster, this wil cause the web server to restart causing a short disruption to connected users.
- Power up the replacement device and complete the initial configuration
- Login to the admin console
- Importing the existing system and user configuration to the replacement device
- Install new licenses on the replacement device. If this is a RMA device, complete the RMA process to install replacement licenses on the device.
During the import of the system and user configuration, it will retain the cluster configuration and allow the replacement device to join the existing cluster.