How HBase replication policies work
After you create the first HBase replication policy between a source cluster and target cluster, the Replication Manager service starts several background processes. After the processes complete, the service initiates the HBase data replication. One of the main background process is the first-time setup configuration.
Steps in first-time setup configuration process
When you create the first HBase replication policy to replicate HBase data from a source cluster to a target cluster, the Replication Manager completes the first-time setup configuration steps and then replicates the data. The first-time setup configuration between a cluster pair is a one-time process, therefore subsequent HBase replication policies for the same cluster pair (ClusterA and ClusterB) do not require a first-time setup.
The first-time setup configuration completes the following steps:
- Creates peers between the source (ClusterA) and target (ClusterB), that is, creates a cluster pair between ClusterA and ClusterB.
- Initiates the required configuration changes. One of the steps ensures that both the clusters use the same credentials.jceks file.
- Restarts the HBase service on both the clusters.
When HBase replication policies are created, modified, or deleted simultaneously, Replication Manager processes each operation independent of each other.
What is a cluster pair
The first-time setup configuration creates peers between the source (ClusterA) and target (ClusterB), that is, creates a cluster pair between ClusterA and ClusterB. If a cluster pair (ClusterA and ClusterB) has one or more active/suspended HBase replication policies between them, you cannot pair either of the clusters with another cluster.
You can use ClusterA or ClusterB with another cluster in an HBase replication policy only if the following conditions are true:
- ClusterA and ClusterB do not have existing HBase replication policies.
- All existing active/suspended HBase replication policies are deleted.
A warning appears on the Select Destination page during HBase replication policy creation if you choose ClusterA or ClusterB as source or target (when no HBase replication policies exist between them) with another cluster or if the other cluster in the cluster pair is unreachable. To continue HBase replication policy creation, you must acknowledge the forced re-pairing of the clusters.