NDB Cluster Internals  /  NDB Cluster Start Phases  /  NDB_STTOR Phase 2

5.8 NDB_STTOR Phase 2

The DBLQH block enables its exchange of internal records with DBTUP and DBACC, while DBTC permits its internal records to be exchanged with DBDIH. The DBDIH kernel block creates the mutexes used by the NDB kernel and reads nodes using the READ_NODESREQ signal. With the data from the response to this signal, DBDIH can create node lists, node groups, and so forth. For node restarts and initial node restarts, DBDIH also asks the master for permission to perform the restart. The master will ask all live nodes if they are prepared to permit the new node to join the cluster. If an initial node restart is to be performed, then all LCPs are invalidated as part of this phase.

LCPs from nodes that are not part of the cluster at the time of the initial node restart are not invalidated. The reason for this is that there is never any chance for a node to become master of a system restart using any of the LCPs that have been invalidated, since this node must complete a node restart—including a local checkpoint—before it can join the cluster and possibly become a master node.

The CMVMI kernel block activates the sending of packed signals, which occurs only as part of database operations. Packing must be enabled prior to beginning any such operations during the execution of the redo log or node recovery phases.

The DBTUX block sets the type of start currently taking place, while the BACKUP block sets the type of restart to be performed, if any (in each case, the block actually sets a variable whose value reflects the type of start or restart). The SUMA block remains inactive during this phase.

The PGMAN kernel block starts the generation of two repeated signals, the first handling cleanup. This signal is sent every 200 milliseconds. The other signal handles statistics, and is sent once per second.