Summary of NDB Cluster Start Phases 23.5.4 Summary of NDB Cluster Start Phases 4475 This section provides a simplified outline of the steps involved when NDB Cluster data nodes are started. More complete information can be found in NDB 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 23.5.1, “Commands in the NDB Cluster Management Client” ). These start phases are also reported in the  start_phase  column of the  ndbinfo.nodes  table. 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: When one or more nodes hang in Phase 1 while the remaining node or nodes hang in Phase 2, this often indicates network problems. One possible cause of such issues is one or more cluster hosts having multiple network interfaces. Disk Data files are not removed when restarting a node using  --initial . Setup and initialization (phase -1).   Prior to startup, each data node ( ndbd  process) must be initialized. Initialization consists of the following steps: Start types.   There are several different startup types and modes, as shown in the following list: • Initial start.   The cluster starts with a clean file system on all data nodes. This occurs either when the cluster started for the very first time, or when all data nodes are restarted using the  --initial  option. • System restart.   The cluster starts and reads data stored in the data nodes. This occurs when the cluster has been shut down after having been in use, when it is desired for the cluster to resume operations from the point where it left off. • Node restart.   This is the online restart of a cluster node while the cluster itself is running. • Initial node restart.   This is the same as a node restart, except that the node is reinitialized and started with a clean file system. 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 • Phase 0.   The  NDBFS  and  NDBCNTR  blocks start. Data node file systems are cleared on those data nodes that were started with  --initial  option. • Phase 1.   In this stage, all remaining  NDB  kernel blocks are started. NDB Cluster connections are set up, inter-block communications are established, and heartbeats are started. In the case of a node restart, API node connections are also checked. Note Note