MapR 5.0 Documentation : Mirroring with Multiple Clusters

To mirror volumes between clusters, create an additional entry in mapr-clusters.conf on the source volume's cluster for each additional cluster that hosts a mirror of the volume. The entry must list the cluster's name, followed by a comma-separated list of hostnames and ports for the cluster's CLDB nodes.

To set up multiple clusters

  1. On each cluster make a note of the cluster name and CLDB nodes (the first line in mapr-clusters.conf)
  2. On each webserver and CLDB node, add the remote cluster's CLDB nodes to /opt/mapr/conf/mapr-clusters.conf, using the following format:
    clustername1  <CLDB> <CLDB> <CLDB>
    [ clustername2  <CLDB> <CLDB> <CLDB> ]
    [ ... ]
    
  3. On each cluster, restart the mapr-webserver service on all nodes where it is running.

To set up cross-mirroring between clusters

You can cross-mirror between clusters, mirroring some volumes from cluster A to cluster B and other volumes from cluster B to cluster A. To set up cross-mirroring, create entries in mapr-clusters.conf as follows:

  • Entries in mapr-clusters.conf on cluster A nodes:
    • First line contains name and CLDB servers of cluster A
    • Second line contains name and CLDB servers of cluster B
  • Entries in mapr-clusters.conf on cluster B nodes:
    • First line contains name and CLDB servers of cluster B
    • Second line contains name and CLDB servers of cluster A

For example, the mapr-clusters.conf file for cluster A with three CLDB nodes (nodeA, nodeB, and nodeC) would look like this:

clusterA <nodeA> <nodeB> <nodeC>
clusterB <nodeD>

The mapr-clusters.conf file for cluster B with one CLDB node (nodeD) would look like this:

clusterB <nodeD>
clusterA <nodeA> <nodeB> <nodeC>

By creating additional entries, you can mirror from one cluster to several others.

Each cluster must already be set up and running. Each cluster must have a unique name. Every node in every cluster must be able to resolve all nodes in other clusters, either through DNS or entries in /etc/hosts.