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Restricted Mode in a Kofax Search and Matching Server Cluster

When working with multiple servers in a Kofax Search and Matching Server cluster, it may be advantageous to have a second load balancer to work as a fallback in case something happens to the other Load Balancer.

This is a problem because a Load Balancer is not allowed to administer a database. It cannot activate, deactivate, add, remove, import, export, or update a database automatically. A cluster works without a master, which means that no data synchronization is managed by the Load Balancer or the Master. Every node in the cluster is added as a slave.

In a typical configuration, the Load Balancer is only allowed to add and remove nodes, but they must also be slaves. If a node is configured as a master, it is rejected from the cluster. Queries to the cluster are distributed between every node independently based on the database version of each node. It is ideal for the database version to be the same on multiple nodes, but if they have different versions, the Load Balancer may create extra traffic to located the node with the best query results. This extra traffic may slow search results for this and other queries.

In order to create a redundancy in cluster design, a second Load Balancer can reference some Kofax Search and Matching Server nodes that are already listed by another Load Balancer. Both load balancers must be referenced in the database properties of the transformation project.

However, in order for the two load balancers to work together without sending contradictory information, they both need to be configured to use "restricted mode." When the Load Balancer and nodes are running in restricted mode, then there is no master node in the cluster. If necessary, slave nodes are references by a second Load Balancer for redundancy.

You can configure a load balancer to use restricted mode by following these steps:

How to set the restricted mode

There are two methods of setting the restricted mode for a load balancer.

  1. Add the SERVICEMODE="restricted" parameter to the command when installing via the MSP file.

  2. Edit the Kofax.KSMS.LoadBalancerService.exe.config file and set the value of the RunningMode to "Restricted".

Once the restricted mode is enabled for each load balancer you can:

  • Add a node to a load balancer

  • Remove a node from a load balancer

  • Update a database