NDB_MGMD(8)

NAME
ndb_mgmd - the MySQL Cluster management server daemon

SYNOPSIS

ndb_mgmd options

DESCRIPTION

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 all MySQL Cluster programs, see Section 17.4.2, “Options Common to MySQL Cluster Programs”.

    • --bind-address=host[:port]
    Command-Line Format | --bind-address
     | Permitted Values
     | Type | string
     | Default | [none]

    When specified, this option limits management server connections by management clients to clients at the specified host name or IP address (and possibly port, if this is also specified). In such cases, a management client attempting to connect to the management server from any other address fails with the error Unable to setup port: host:port!

    If the port is not specified, the management client attempts to use port 1186.

    • --no-nodeid-checks
    Command-Line Format | --no-nodeid-checks
     | Permitted Values
     | Type | boolean
     | Default | FALSE

    Do not perform any checks of node IDs.

    • --configdir=path
    Command-Line Format | --configdir=directory
     | --config-dir=directory
     | Permitted Values
     | Type | file name
     | Default | $INSTALLDIR/mysql-cluster

    Specifies the cluster management server's configuration cache directory. --config-dir is an alias for this option.

    • This option, whose default value is 1 (or TRUE, or ON), can be used to disable the management server's configuration cache, so that it reads its configuration from config.ini every time it starts (see Section 17.3.2, “MySQL Cluster Configuration Files”). You can do this by starting the ndb_mgmd process with any one of the following options:

        • --config-cache=0

        • --config-cache=FALSE

        • --config-cache=OFF

        • --skip-config-cache
        Using one of the options just listed is effective only if the management server has no stored configuration at the time it is started. If the management server finds any configuration cache files, then the --config-cache option or the --skip-config-cache option is ignored. Therefore, to disable configuration caching, the option should be used the first time that the management server is started. Otherwise—that is, if you wish to disable configuration caching for a management server that has already created a configuration cache—you must stop the management server, delete any existing configuration cache files manually, then restart the management server with --skip-config-cache (or with --config-cache set equal to 0, OFF, or FALSE).

        Configuration cache files are normally created in a directory named mysql-cluster under the installation directory (unless this location has been overridden using the --configdir option). Each time the management server updates its configuration data, it writes a new cache file. The files are named sequentially in order of creation using the following format:

            ndb_node-id_config.bin.seq-number

        node-id is the management server's node ID; seq-number is a sequence number, beginning with 1. For example, if the management server's node ID is 5, then the first three configuration cache files would, when they are created, be named ndb_5_config.bin.1, ndb_5_config.bin.2, and ndb_5_config.bin.3.

        If your intent is to purge or reload the configuration cache without actually disabling caching, you should start ndb_mgmd with one of the options --reload or --initial instead of --skip-config-cache.

        To re-enable the configuration cache, simply restart the management server, but without the --config-cache or --skip-config-cache option that was used previously to disable the configuration cache.

        Beginning with MySQL Cluster NDB 7.2.5, ndb_mgmd no longer checks for the configuration directory (--configdir) or attempts to create one when --skip-config-cache is used. (Bug #13428853)

        • --config-file=filename, -f filename
        Command-Line Format | --config-file
         | -f
         | -c
         | Permitted Values
         | Type | file name
         | Default | ./config.ini

        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 is ignored unless the management server is forced to read the configuration file, either because ndb_mgmd was started with the --reload or --initial option, or because the management server could not find any configuration cache. This option is also read if ndb_mgmd was started with --config-cache=OFF. See Section 17.3.2, “MySQL Cluster Configuration Files”, for more information.

        • --mycnf
        Command-Line Format | --mycnf
         | Permitted Values
         | Type | boolean
         | Default | FALSE

        Read configuration data from the my.cnf file.

        • --daemon, -d
        Command-Line Format | --daemon
         | -d
         | Permitted Values
         | Type | boolean
         | Default | TRUE

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

        This option has no effect when running ndb_mgmd on Windows platforms.

        • --interactive
        Command-Line Format | --interactive
         | Permitted Values
         | Type | boolean
         | Default | FALSE

        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.

        • --initial
        Command-Line Format | --initial
         | Permitted Values
         | Type | boolean
         | Default | FALSE

        Configuration data is cached internally, rather than being read from the cluster global configuration file each time the management server is started (see Section 17.3.2, “MySQL Cluster Configuration Files”). Using the --initial option overrides this behavior, by forcing the management server to delete any existing cache files, and then to re-read the configuration data from the cluster configuration file and to build a new cache.

        This differs in two ways from the --reload option. First, --reload forces the server to check the configuration file against the cache and reload its data only if the contents of the file are different from the cache. Second, --reload does not delete any existing cache files.

        If ndb_mgmd is invoked with --initial but cannot find a global configuration file, the management server cannot start.

        When a management server starts, it checks for another management server in the same MySQL Cluster and tries to use the other management server's configuration data; ndb_mgmd ignores --initial unless it is the only management server running. This behavior also has implications when performing a rolling restart of a MySQL Cluster with multiple management nodes. See Section 17.5.4, “Performing a Rolling Restart of a MySQL Cluster”, for more information.

        • --log-name=name
        Command-Line Format | --log-name=
         | Permitted Values
         | Type | string
         | Default | MgmtSrvr

        Provides a name to be used for this node in the cluster log.

        • --nodaemon
        Command-Line Format | --nodaemon
         | Permitted Values
         | Type | boolean
         | Default | FALSE
         | Permitted Values
         | Type (windows) | boolean
         | Default | TRUE

        Instructs ndb_mgmd not to start as a daemon process.

        The default behavior for ndb_mgmd on Windows is to run in the foreground, making this option unnecessary on Windows platforms.

        • --print-full-config, -P
        Command-Line Format | --print-full-config
         | -P
         | Permitted Values
         | Type | boolean
         | Default | FALSE

        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.

        • --reload
        Command-Line Format | --reload
         | Permitted Values
         | Type | boolean
         | Default | FALSE

        In MySQL Cluster NDB 7.2, configuration data is stored internally rather than being read from the cluster global configuration file each time the management server is started (see Section 17.3.2, “MySQL Cluster Configuration Files”). Using this option forces the management server to check its internal data store against the cluster configuration file and to reload the configuration if it finds that the configuration file does not match the cache. Existing configuration cache files are preserved, but not used.

        This differs in two ways from the --initial option. First, --initial causes all cache files to be deleted. Second, --initial forces the management server to re-read the global configuration file and construct a new cache.

        If the management server cannot find a global configuration file, then the --reload option is ignored.

        When a management server starts, it checks for another management server in the same MySQL Cluster and tries to use the other management server's configuration data; ndb_mgmd ignores --reload unless it is the only management server running. This behavior also has implications when performing a rolling restart of a MySQL Cluster with multiple management nodes. See Section 17.5.4, “Performing a Rolling Restart of a MySQL Cluster”, for more information.

        • --nowait-nodes
        Command-Line Format | --nowait-nodes=list
         | Permitted Values
         | Type | numeric
         | Default |
         | Range | 1 .. 255

        When starting a MySQL Cluster is configured with two management nodes, each management server normally checks to see whether the other ndb_mgmd is also operational and whether the other management server's configuration is identical to its own. However, it is sometimes desirable to start the cluster with only one management node (and perhaps to allow the other ndb_mgmd to be started later). This option causes the management node to bypass any checks for any other management nodes whose node IDs are passed to this option, permitting the cluster to start as though configured to use only the management node that was started.

        For purposes of illustration, consider the following portion of a config.ini file (where we have omitted most of the configuration parameters that are not relevant to this example):

            [ndbd]
            NodeId = 1
            HostName = 192.168.0.101
            [ndbd]
            NodeId = 2
            HostName = 192.168.0.102
            [ndbd]
            NodeId = 3
            HostName = 192.168.0.103
            [ndbd]
            NodeId = 4
            HostName = 192.168.0.104
            [ndb_mgmd]
            NodeId = 10
            HostName = 192.168.0.150
            [ndb_mgmd]
            NodeId = 11
            HostName = 192.168.0.151
            [api]
            NodeId = 20
            HostName = 192.168.0.200
            [api]
            NodeId = 21
            HostName = 192.168.0.201

        Assume that you wish to start this cluster using only the management server having node ID 10 and running on the host having the IP address 192.168.0.150. (Suppose, for example, that the host computer on which you intend to the other management server is temporarily unavailable due to a hardware failure, and you are waiting for it to be repaired.) To start the cluster in this way, use a command line on the machine at 192.168.0.150 to enter the following command:

            shell> ndb_mgmd --ndb-nodeid=10 --nowait-nodes=11

        As shown in the preceding example, when using --nowait-nodes, you must also use the --ndb-nodeid option to specify the node ID of this ndb_mgmd process.

        You can then start each of the cluster's data nodes in the usual way. If you wish to start and use the second management server in addition to the first management server at a later time without restarting the data nodes, you must start each data node with a connectstring that references both management servers, like this:

            shell> ndbd -c 192.168.0.150,192.168.0.151

        The same is true with regard to the connectstring used with any mysqld processes that you wish to start as MySQL Cluster SQL nodes connected to this cluster. See Section 17.3.2.3, “The MySQL Cluster Connectstring”, for more information.

        When used with ndb_mgmd, this option affects the behavior of the management node with regard to other management nodes only. Do not confuse it with the --nowait-nodes option used with ndbd or ndbmtd to permit a cluster to start with fewer than its full complement of data nodes; when used with data nodes, this option affects their behavior only with regard to other data nodes.

        Multiple management node IDs may be passed to this option as a comma-separated list. Each node ID must be no less than 1 and no greater than 255. In practice, it is quite rare to use more than two management servers for the same MySQL Cluster (or to have any need for doing so); in most cases you need to pass to this option only the single node ID for the one management server that you do not wish to use when starting the cluster.

            Note
            When you later start the “missing” management server, its configuration must match that of the management server that is already in use by the cluster. Otherwise, it fails the configuration check performed by the existing management server, and does not start.

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

    See Section 17.3.2.3, “The MySQL Cluster Connectstring”, for information about using connectstrings. ndb_mgmd(8), 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”.

        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.)

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

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

        • --install[=name]
        Command-Line Format | --install[=name]
         | Permitted Values
         | Type (windows) | string
         | Default | ndb_mgmd

        Causes ndb_mgmd to be installed as a Windows service. Optionally, you can specify a name for the service; if not set, the service name defaults to ndb_mgmd. Although it is preferable to specify other ndb_mgmd program options in a my.ini or my.cnf configuration file, it is possible to use them together with --install. However, in such cases, the --install option must be specified first, before any other options are given, for the Windows service installation to succeed.

        It is generally not advisable to use this option together with the --initial option, since this causes the configuration cache to be wiped and rebuilt every time the service is stopped and started. Care should also be taken if you intend to use any other ndb_mgmd options that affect the starting of the management server, and you should make absolutely certain you fully understand and allow for any possible consequences of doing so.

        The --install option has no effect on non-Windows platforms.

        • --remove[=name]
        Command-Line Format | --remove[=name]
         | Permitted Values
         | Type (windows) | string
         | Default | ndb_mgmd

        Causes an ndb_mgmd process that was previously installed as a Windows service to be removed. Optionally, you can specify a name for the service to be uninstalled; if not set, the service name defaults to ndb_mgmd.

        The --remove option has no effect on non-Windows platforms.

COPYRIGHT

Copyright © 1997, 2012, Oracle and/or its affiliates. All rights reserved.

This documentation is free software; you can redistribute it and/or modify it only under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License.

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SEE ALSO
For more information, please refer to the MySQL Reference Manual, which may already be installed locally and which is also available online at http://dev.mysql.com/doc/.

AUTHOR
Oracle Corporation (http://dev.mysql.com/).