Replication State in Zookeeper
HBase replication maintains its state in ZooKeeper. By default, the state is contained in the base node
/hbase/replication. This node contains two child nodes, the Peers znode and the RS
znode.
The Peers Znode
The peers znode is stored in
/hbase/replication/peers by default. It consists of a list of all peer
replication clusters along with the status of each of them. The value of each peer is its
cluster key, which is provided in the HBase shell. The cluster key contains a list of
ZooKeeper nodes in the cluster quorum, the client port for the ZooKeeper quorum, and the
base znode for HBase in HDFS on that cluster.
The RS Znode
The rs znode contains a list of WAL logs which
need to be replicated. This list is divided into a set of queues organized by Region
Server and the peer cluster that the Region Server is shipping the logs to. The
rs znode has one child znode for each Region Server in the cluster. The
child znode name is the Region Server hostname, client port, and start code. This list
includes both live and dead Region Servers.
