What is an arbitrator?
If one or more nodes in a cluster fail, it is possible that not all cluster nodes will be able to see one another. In fact, it is possible that two sets of nodes might become isolated from one another in a network partitioning, also known as a split brain scenario. This type of situation is undesirable because each set of nodes tries to behave as though it is the entire cluster. When cluster nodes go down, there are two possibilities. If more than 50% of the remaining nodes can communicate with each other, we have what is sometimes called a majority rules situation, and this set of nodes is considered to be the cluster. The arbitrator comes into play when there is an even number of nodes: in such cases, the set of nodes to which the arbitrator belongs is considered to be the cluster, and nodes not belonging to this set are shut down. The preceding information is somewhat simplified. A more complete explanation taking into account node groups follows: When all nodes in at least one node
If one or more data nodes in a cluster fail, it is possible that not all cluster data nodes will be able to “see” one another. In fact, it is possible that two sets of data nodes might become isolated from one another in a network partitioning, also known as a “split-brain” scenario. This type of situation is undesirable because each set of data nodes tries to behave as though it is the entire cluster. When cluster data nodes go down, there are two possibilities. If more than 50% of the remaining data nodes can communicate with each other, we have what is sometimes called a “majority rules” situation, and this set of data nodes is considered to be the cluster. The arbitrator comes into play when there is an even number of data nodes: in such cases, the set of nodes to which the arbitrator belongs is considered to be the cluster, and any data or management nodes not belonging to this set are shut down. The preceding information is somewhat simplified. A more complete explanation taking
