The cluster members file

Each node in a Failover Manager cluster has a cluster members file (by default named efm.nodes) that contains a list of the current Failover Manager cluster members. When an agent starts, it uses the file to locate other cluster members. The Failover Manager installer creates a file template for the cluster members file named efm.nodes.in in the /etc/edb/efm-4.<x> directory.

After completing the Failover Manager installation, make a working copy of the template:

cp /etc/edb/efm-4.4/efm.nodes.in /etc/edb/efm-4.4/efm.nodes

After copying the template file, change the owner of the file to efm:

chown efm:efm efm.nodes

By default, Failover Manager expects the cluster members file to be named efm.nodes. If you name the cluster members file something other than efm.nodes, modify the Failover Manager service script to instruct Failover Manager to use the new name.

The cluster members file on the first node started can be empty. This node becomes the membership coordinator. On each subsequent node, the cluster member file must contain the address and port number of the membership coordinator. Each entry in the cluster members file must be listed in an address:port format. Separate multiple entries with a space.

The agents update the contents of the efm.nodes file to match the current members of the cluster. As agents join or leave the cluster, the efm.nodes files on other agents are updated to reflect the current cluster membership. If you invoke the `efm stop-cluster <../07_using_efm_utility/#efm_stop_cluster>`__ command, Failover Manager doesn’t modify the file.

If the membership coordinator leaves the cluster, another node assumes the role. You can use the `efm cluster-status <../07_using_efm_utility/#efm_cluster_status>`__ command to find the address of the membership coordinator. If a node joins or leaves a cluster while an agent is down, before starting that agent, manually ensure that the file includes at least the current membership coordinator address and port.

If you know the addresses and ports of the nodes that are joining the cluster, you can include the addresses in the cluster members file at any time. At startup, any addresses that don’t identify cluster members are ignored unless the auto.allow.hosts property in the `cluster properties file <01_cluster_properties/#auto_allow_hosts>`__ is set to true.

If the stable.nodes.file property in the cluster properties file) is set to true, the agent doesn’t update the .nodes file when cluster members join or leave the cluster. This behavior is most useful when the IP addresses of cluster members don’t change often.