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16.4.4.4. Defining the MySQL Cluster Management Server

The [NDB_MGMD] section is used to configure the behavior of the management server. [MGM] can be used as an alias; the two section names are equivalent. All parameters in the following list are optional and assume their default values if omitted. Note: If neither the ExecuteOnComputer nor the HostName parameter is present, the default value localhost will be assumed for both.

  • Id

    Each node in the cluster has a unique identity, which is represented by an integer value in the range 1 to 63 inclusive. This ID is used by all internal cluster messages for addressing the node.

  • ExecuteOnComputer

    This refers to one of the computers defined in the [COMPUTER] section.

  • PortNumber

    This is the port number on which the management server listens for configuration requests and management commands.

  • LogDestination

    This parameter specifies where to send cluster logging information. There are three options in this regard: CONSOLE, SYSLOG, and FILE:

    • CONSOLE outputs the log to stdout:

      CONSOLE
      
    • SYSLOG sends the log to a syslog facility, possible values being one of auth, authpriv, cron, daemon, ftp, kern, lpr, mail, news, syslog, user, uucp, local0, local1, local2, local3, local4, local5, local6, or local7.

      Note: Not every facility is necessarily supported by every operating system.

      SYSLOG:facility=syslog
      
    • FILE pipes the cluster log output to a regular file on the same machine. The following values can be specified:

      • filename: The name of the logfile.

      • maxsize: The maximum size (in bytes) to which the file can grow before logging rolls over to a new file. When this occurs, the old logfile is renamed by appending .N to the filename, where N is the next number not yet used with this name.

      • maxfiles: The maximum number of logfiles.

      FILE:filename=cluster.log,maxsize=1000000,maxfiles=6
      

      It is possible to specify multiple log destinations separated by semicolons as shown here:

      CONSOLE;SYSLOG:facility=local0;FILE:filename=/var/log/mgmd
      

      The default value for the FILE parameter is FILE:filename=ndb_node_id_cluster.log,maxsize=1000000,maxfiles=6, where node_id is the ID of the node.

  • ArbitrationRank

    This parameter is used to define which nodes can act as arbitrators. Only MGM nodes and SQL nodes can be arbitrators. ArbitrationRank can take one of the following values:

    • 0: The node will never be used as an arbitrator.

    • 1: The node has high priority; that is, it will be preferred as an arbitrator over low-priority nodes.

    • 2: Indicates a low-priority node which be used as an arbitrator only if a node with a higher priority is not available for that purpose.

    Normally, the management server should be configured as an arbitrator by setting its ArbitrationRank to 1 (the default value) and that of all SQL nodes to 0.

  • ArbitrationDelay

    An integer value which causes the management server's responses to arbitration requests to be delayed by that number of milliseconds. By default, this value is 0; it is normally not necessary to change it.

  • DataDir

    This specifies the directory where output files from the management server will be placed. These files include cluster log files, process output files, and the daemon's process ID (PID) file. (For log files, this location can be overridden by setting the FILE parameter for LogDestination as discussed previously in this section.)


 
 
  Published under the terms of the GNU General Public License Design by Interspire