Find
Found found between the nodes each other, a process of forming the cluster. This scene has many processes that occur, for example: you start a cluster node, or a node confirmation master node has hung up, or a new master node is elected.
When we configure a cluster configuration in a configuration file discovery.seed_hosts, this is the seed list of addresses, the cluster nodes are in the address list. Discovery process is divided into two stages:
- Each node is connected to the node address will seed the address list, and to confirm that these nodes are not the primary node with qualifications.
- If the validation is successful, the node will share a list of seed addresses to the remote node and the remote node to share his seed will address list for this node. This node will then ask his new node discovery, and finally the formation of clusters.
If a node does not have the qualifications master node, then he will look for the master node has elected. If the master node is not found, it will follow discovery.find_peers_intervalthe retry time configuration.
If the master node has several qualifications, it will look for a master node (already elected), or to discover all but qualified node has the master node is not the master node, and the completion of the electoral process, the election of the master node.
The role of the master node
Lightweight master node cluster is responsible for aspects of the action, such as: create or delete the index, tracking the cluster nodes, decided to slice assigned to which node in the cluster rebalancing process, how to move data between nodes, etc. . A cluster have a stable master node is very important.