Setting Up Cross-Mirroring Between Unsecure Clusters

Describes how to edit the mapr-clusters.conf file to mirror volumes between unsecure clusters.

To mirror volumes between unsecure clusters, start by editing the mapr-clusters.conf file on the cluster of the source volume and create an entry for each additional cluster that hosts a mirror of the volume. The entry must list the name of the cluster, followed by a space-separated list of hostnames and ports for the CLDB nodes of the cluster. In addition, use the secure parameter to specify whether the clusters are secure or non-secure. See Configuring Secure Clusters for Cross-Cluster Mirroring and Replication for more information about generating tickets for secure clusters.

Note: When mirroring between clusters, servers in one cluster cannot use the same IP addresses as servers in the other cluster. For example, if node A in cluster A has a private IP address 10.10.20.29, no server in cluster B can have the same private IP address. Also, all the servers in one cluster must be able to reach all the servers in the other cluster and vice versa. For example, suppose 10.10.20.29 is the only IP address used by node A in cluster A; then all servers in cluster B should be able to reach the IP address 10.10.20.29.

To set up cross-mirroring between unsecure clusters:

Review the requirements for Creating Remote Mirrors before you begin.
On each cluster, make a note of the cluster name and CLDB nodes (the first line in mapr-clusters.conf)
On each webserver and CLDB node, add the CLDB nodes of the remote cluster to /opt/mapr/conf/mapr-clusters.conf, using the following format:
```
clustername1  <CLDB> <CLDB> <CLDB>
[ clustername2  <CLDB> <CLDB> <CLDB> ]
[ ... ]
```
For example, suppose you have a cluster, clusterA, with two CLDB nodes, nodeA and nodeB. Now you want to add a second cluster called clusterB with CLDB nodes nodeC and nodeD. Edit the mapr-clusters.conf file and add the line for clusterB as shown:
```
clusterA nodeA:7222 nodeB:7222
clusterB nodeC:7222 nodeD:7222
```
Warning: You must include the port number in the CLDB hostname notation.
Here:
1. First line contains cluster name and CLDB nodes of cluster A (the local cluster)
2. Second line contains cluster name and CLDB nodes of cluster B (the remote cluster)
The mapr-clusters.conf file for cluster B with 2 CLDB nodes (nodeC and nodeD) looks as follows:
```
clusterB nodeC:7222 nodeD:7222
clusterA nodeA:7222 nodeB:7222
```
By creating additional entries in the mapr-clusters.conf file, you can mirror from one cluster to several others.
Set secure=false if both clusters are not secure. If both the clusters are secure, see Configuring Secure Clusters for Cross-Cluster Mirroring and Replication for more information.

Warning: Mirroring only works between two secure clusters or between two non-secure clusters. Mirroring does not work when one cluster is secure and the other is non-secure.
On each cluster, restart the mapr-apiserver service on all nodes where it is running.