Types of Redundant Licensing
When working with Redundancy, both nodes will require a license. However, there are two approaches that are detailed below. In both cases, the license for the Backup node generally contains most, if not all, the same modules as the Master node. For example, if the Master is storing history with the SQL Bridge module, then the Backup would also require the module in the event a failover occurs, otherwise data would be lost.
However, non-critical modules do not need to be added to the Backup License. The Master license could make use of the Symbol Factory module, and since the Designer only connects to the Master node, there is no reason to add this module to the Backup node.
Two Standard Licenses - Classic Redundancy
Traditionally, Redundancy involves two standard licenses: one license will be applied to the Master Gateway, and the other license will be applied to the Backup Gateway. Since two standard licenses are being used, this approach allows users to disable Redundancy, and set both Gateways to independent modes.
Backup-Only Licenses
Backup-Only licenses are available for purchase. This license force the Gateway into a Backup mode, and the mode can not be changed while the license is applied. The benefit of this type of license is that they come at a discounted price. For more details, contact your Account Representative.
If using a Backup only license, the Mode property on the Backup Gateway's Redundancy page will look like the image below.
Instead of the dropdown list that normally appears on this property, the license has forced this Gateway into a Backup mode.
If you would like to change the mode of this Gateway, the backup-only license must first be unactivated. Once unactivated, a new license will need to be applied, otherwise the Gateway will operate in 2 hour trial mode.