When a server is installed, it can be added to an existing topology, which will clone the server's configuration. Topology settings are designed to operate without additional configuration. If required, some settings can be adjusted to fit the needs of the environment.

Server configuration settings

Configuration settings for the topology are configured in the Global Configuration and in the Config File Handler Backend. Though they are topology settings, they are unique to each server and are not mirrored. Settings must be kept the same on all servers.

The Global Configuration object contains a single topology setting, force-as-master-for-mirrored-data. This should be set to true on only one of the servers in the topology, and is used only if a situation occurs where the topology cannot determine a primary because a majority of servers is not available. A server with this setting enabled will be assigned the role of primary if no suitable primary can be determined. See Topology primary requirements and selection for details about how a primary is selected for a topology.

The Config File Handler Backend defines three topology (mirrored-subtree) settings:

  • mirrored-subtree-peer-polling-interval – Specifies the frequency at which the server polls its topology peers to determine if there are any changes that might warrant a new primary selection. A lower value will ensure a faster failover, but it will also cause more traffic among the peers. The default value is five seconds. If no suitable primary is found, the polling frequency is adjusted to 100 milliseconds until a new primary is selected.
  • mirrored-subtree-entry-update-timeout – Specifies the maximum length of time to wait for an update operation (add, delete, modify or modify-dn) on an entry to be applied by the primary on all of the servers in the topology. The default is 10 seconds. In reality, updates can take up to twice as much time as this timeout value if primary selection is in progress at the time the update operation was received.
  • mirrored-subtree-search-timeout – Specifies the maximum length of time in milliseconds to wait for search operations to complete. The default is 10 seconds.

Topology settings

Topology meta-data is stored under the cn=topology,cn=config subtree and cluster data is stored under the cn=cluster,cn=config subtree. The only setting that can be changed is the cluster name.