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-4.0 directory.

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

# cp /etc/edb/efm-4.0/efm.nodes.in /etc/edb/efm-4.0/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, you must 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 will become 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, with multiple entries separated by white space.

The Membership Coordinator will 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 command, Failover Manager does not modify the file.

If the Membership Coordinator leaves the cluster, another node will assume the role. You can use the 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, you must manually ensure that the file includes at least the current Membership Coordinator.

If you know the IP addresses and ports of the nodes that will be joining the cluster, you can include the addresses in the cluster members file at any time. At startup, any addresses that do not identify cluster members will be ignored unless the auto.allow.hosts property (in the cluster properties file) is set to true.

If the stable.nodes.file property (located in the cluster properties file) is set to true, the Membership Coordinator will not update the .nodes file when cluster members join or leave the cluster; this behavior is most useful when the IP addresses of cluster members do not change often.