17.5.1 Summary of MySQL Cluster Start Phases

This section provides a simplified outline of the steps involved when MySQL Cluster data nodes are started. More complete information can be found in MySQL Cluster Start Phases, in the NDB Internals Guide.

These phases are the same as those reported in the output from the node_id STATUS command in the management client (see Section 17.5.2, “Commands in the MySQL Cluster Management Client”). These start phases are also reported in the start_phase column of the ndbinfo.nodes table.

Start types.  There are several different startup types and modes, as shown in the following list:

Setup and initialization (phase -1).  Prior to startup, each data node (ndbd process) must be initialized. Initialization consists of the following steps:

  1. Obtain a node ID

  2. Fetch configuration data

  3. Allocate ports to be used for inter-node communications

  4. Allocate memory according to settings obtained from the configuration file

When a data node or SQL node first connects to the management node, it reserves a cluster node ID. To make sure that no other node allocates the same node ID, this ID is retained until the node has managed to connect to the cluster and at least one ndbd reports that this node is connected. This retention of the node ID is guarded by the connection between the node in question and ndb_mgmd.

After each data node has been initialized, the cluster startup process can proceed. The stages which the cluster goes through during this process are listed here:

After this process is completed for an initial start or system restart, transaction handling is enabled. For a node restart or initial node restart, completion of the startup process means that the node may now act as a transaction coordinator.