MySQL Clusters can survive the failure of any single storage node as long as NoOfReplicas
is greater than 1
(and there is almost no point in a cluster if it is not). In this recipe, we will demonstrate how a MySQL Cluster detects and handles the failure of a single storage node (where all other nodes are working). In the next recipe, we will cover how a cluster copes with multiple storage node failures.
MySQL Cluster has an algorithm for high availability with two, slightly competing, aims:
Prevent database inconsistencies in the event of a split-brain
Keep the database up and running (that is, to keep the database users happy)
In every MySQL Cluster, there are many copies of each fragment of data (using NoOfReplicas
). If we consider the common case where NoOfReplicas
equals to 2
, then each fragment of data is stored on two nodes, and therefore, each nodegroup consists of two nodes with identical data.
In the next section, we will demonstrate the failure...