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17.4.2 ndb_mgmd — The MySQL Cluster Management Server Daemon

The management server is the process that reads the cluster configuration file and distributes this information to all nodes in the cluster that request it. It also maintains a log of cluster activities. Management clients can connect to the management server and check the cluster's status.

The following table includes options that are specific to the MySQL Cluster management server program ndb_mgmd. Additional descriptions follow the table. For options common to most MySQL Cluster programs (including ndb_mgmd), see Section 17.4.20, “Options Common to MySQL Cluster Programs — Options Common to MySQL Cluster Programs”.

Table 17.27 This table describes command-line options for the ndb_mgmd program

Format Description Added or Removed




Specify the cluster configuration file; in NDB-6.4.0 and later, needs --reload or --initial to override configuration cache if present

All MySQL 5.0 based releases



Print full configuration and exit

ADDED: 5.0.10



Run ndb_mgmd in daemon mode (default)

All MySQL 5.0 based releases


Do not run ndb_mgmd as a daemon

All MySQL 5.0 based releases


Run ndb_mgmd in interactive mode (not officially supported in production; for testing purposes only)

All MySQL 5.0 based releases


Do not provide any node id checks

All MySQL 5.0 based releases


Read cluster configuration data from the my.cnf file

All MySQL 5.0 based releases

  • --no-nodeid-checks

    Command-Line Format--no-nodeid-checks
    Permitted ValuesTypeboolean

    Do not perform any checks of node IDs.

  • --config-file=filename, -f filename

    Command-Line Format--config-file=file
    Permitted ValuesTypefile name

    Instructs the management server as to which file it should use for its configuration file. By default, the management server looks for a file named config.ini in the same directory as the ndb_mgmd executable; otherwise the file name and location must be specified explicitly.

    This option also can be given as -c file_name, but this shortcut is obsolete and should not be used in new installations.

  • --mycnf

    Command-Line Format--mycnf
    Permitted ValuesTypeboolean

    Read configuration data from the my.cnf file.

  • --daemon, -d

    Command-Line Format--daemon
    Permitted ValuesTypeboolean

    Instructs ndb_mgmd to start as a daemon process. This is the default behavior.

  • --interactive

    Command-Line Format--interactive
    Permitted ValuesTypeboolean

    Starts ndb_mgmd in interactive mode; that is, an ndb_mgm client session is started as soon as the management server is running. This option does not start any other MySQL Cluster nodes.

  • --nodaemon

    Command-Line Format--nodaemon
    Permitted ValuesTypeboolean

    Instructs ndb_mgmd not to start as a daemon process.

  • --print-full-config, -P

    Command-Line Format--print-full-config
    Permitted ValuesTypeboolean

    Shows extended information regarding the configuration of the cluster. With this option on the command line the ndb_mgmd process prints information about the cluster setup including an extensive list of the cluster configuration sections as well as parameters and their values. Normally used together with the --config-file (-f) option.

It is not strictly necessary to specify a connection string when starting the management server. However, if you are using more than one management server, a connection string should be provided and each node in the cluster should specify its node ID explicitly.

See Section, “MySQL Cluster Connection Strings”, for information about using connection strings. Section 17.4.2, “ndb_mgmd — The MySQL Cluster Management Server Daemon”, describes other options for ndb_mgmd.

The following files are created or used by ndb_mgmd in its starting directory, and are placed in the DataDir as specified in the config.ini configuration file. In the list that follows, node_id is the unique node identifier.

  • config.ini is the configuration file for the cluster as a whole. This file is created by the user and read by the management server. Section 17.3, “MySQL Cluster Configuration”, discusses how to set up this file.

  • ndb_node_id_cluster.log is the cluster events log file. Examples of such events include checkpoint startup and completion, node startup events, node failures, and levels of memory usage. A complete listing of cluster events with descriptions may be found in Section 17.5, “Management of MySQL Cluster”.

    By default, when the size of the cluster log reaches one million bytes, the file is renamed to ndb_node_id_cluster.log.seq_id, where seq_id is the sequence number of the cluster log file. (For example: If files with the sequence numbers 1, 2, and 3 already exist, the next log file is named using the number 4.) You can change the size and number of files, and other characteristics of the cluster log, using the LogDestination configuration parameter.

  • ndb_node_id_out.log is the file used for stdout and stderr when running the management server as a daemon.

  • is the process ID file used when running the management server as a daemon.

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