MySQL 5.0 Reference Manual  /  ...  /  Commands in the MySQL Cluster Management Client

17.5.2 Commands in the MySQL Cluster Management Client

In addition to the central configuration file, a cluster may also be controlled through a command-line interface available through the management client ndb_mgm. This is the primary administrative interface to a running cluster.

Commands for the event logs are given in Section 17.5.6, “Event Reports Generated in MySQL Cluster”; commands for creating backups and restoring from them are provided in Section 17.5.3, “Online Backup of MySQL Cluster”.

The management client has the following basic commands. In the listing that follows, node_id denotes either a database node ID or the keyword ALL, which indicates that the command should be applied to all of the cluster's data nodes.

  • HELP

    Displays information on all available commands.

  • SHOW

    Displays information on the cluster's status.

    Note

    In a cluster where multiple management nodes are in use, this command displays information only for data nodes that are actually connected to the current management server.

  • node_id START

    Brings online the data node identified by node_id (or all data nodes).

    Beginning with MySQL 5.0.19, this command can also be used to individual management nodes online.

    Note

    ALL START continues to affect data nodes only.

    Important

    To use this command to bring a data node online, the data node must have been started using ndbd --nostart or ndbd -n.

  • node_id STOP

    Stops the data node identified by node_id (or all data nodes).

    Beginning with MySQL 5.0.19, this command can also be used to stop individual management nodes.

    Note

    ALL STOP continues to affect data nodes only.

    A node affected by this command disconnects from the cluster, and its associated ndbd or ndb_mgmd process terminates.

  • node_id RESTART [-n] [-i]

    Restarts the data node identified by node_id (or all data nodes).

    Using the -i option with RESTART causes the data node to perform an initial restart; that is, the node's file system is deleted and recreated. The effect is the same as that obtained from stopping the data node process and then starting it again using ndbd --initial from the system shell.

    Using the -n option causes the data node process to be restarted, but the data node is not actually brought online until the appropriate START command is issued. The effect of this option is the same as that obtained from stopping the data node and then starting it again using ndbd --nostart or ndbd -n from the system shell.

  • node_id STATUS

    Displays status information for the data node identified by node_id (or for all data nodes).

  • ENTER SINGLE USER MODE node_id

    Enters single user mode, whereby only the MySQL server identified by the node ID node_id is permitted to access the database.

    Important

    Do not attempt to have data nodes join the cluster while it is running in single user mode. Doing so can cause subsequent multiple node failures. Beginning with MySQL 5.0.29, it is no longer possible to add nodes while in single user mode. (See Bug #20395 for more information.)

  • EXIT SINGLE USER MODE

    Exits single user mode, enabling all SQL nodes (that is, all running mysqld processes) to access the database.

    Note

    It is possible to use EXIT SINGLE USER MODE even when not in single user mode, although the command has no effect in this case.

  • QUIT, EXIT

    Terminates the management client.

    This command does not affect any nodes connected to the cluster.

  • SHUTDOWN

    Shuts down all cluster data nodes and management nodes. To exit the management client after this has been done, use EXIT or QUIT.

    This command does not shut down any SQL nodes or API nodes that are connected to the cluster.


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