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3.4.1. The create cluster Command

create cluster {--package=|-P }package_name 
    {--processhosts=|-R }process_host_list cluster_name
    [--verbose | -v]

process_host_list:
    process_name@host[,process_name@host[,...]]

process_name:
    {ndb_mgmd|ndbd|ndbmtd|mysqld|ndbapi}

This command creates a cluster to be managed by the MySQL Cluster Manager. However, it does not start the cluster (see Section 3.4.3, “The start cluster Command”).

create cluster requires the following arguments:

  • A package_name, supplied as the value of the --package option (short form: -P). This must be the name of a package previously registered using add package (see Section 3.3.1, “The add package Command”).

  • A list (process_host_list) of MySQL Cluster processes and the hosts on which they are to run, supplied as the value of the --processhosts option (short form: -R), with list items separated by commas. As with other lists passed as option values in MySQL Cluster Manager commands, you must not use spaces before or after the commas.

    Each item in the process_host_list consists of the name of a MySQL Cluster process joined with the name of the host on which it is located using an amphora (@) sign (also sometimes know as the “at” sign). Permitted values for processes are ndb_mgmd, ndbd, and mysqld. When the cluster employs MySQL Cluster NDB 7.0 or later, you can also use ndbmtd as process name. In other words, a valid process name is the name of a MySQL Cluster process daemon binary.

    To support running your own NDB API applications with a cluster under MySQL Cluster Manager, it is also possible to use ndbapi as a process type. Such applications can be connected to a managed cluster. Currently, MySQL Cluster Manager recognises only that an NDB API application is connected to the cluster; the NDB API application itself must be started, stopped, and configured manually.

    It is also possible to specify one or more “free” mysqld and ndbapi processes without any hosts. To do this, simply use the wildcard * (asterisk character) in place of the hostname or IP address, like this:

    “Free” mysqld process: mysqld@*
    “Free” ndbapi process: ndbapi@*

    A mysqld process or ndbapi process that is specified without a host in this fashion is permitted to connect to the cluster from any host that can access the cluster over the network. Otherwise, the process may connect to the cluster only from the specified host.

    By convention, items in the process_host_list are listed according to the process type, in the following order:

    1. Management node processes (ndb_mgmd)

    2. Data node processes (MySQL Cluster NDB 6.3: ndbd; MySQL Cluster NDB 7.0 and later: ndbd, ndbmtd)

    3. SQL node processes (mysqld)

    4. Custom NDB API applications (ndbapi)

      Note

      For information about writing your own NDB API applications, see The NDB API, in the MySQL CLuster API Developer Guide.

    While the order in which the items are listed does not affect whether the create cluster command succeeds, we suggest that you follow this convention for readability, as well as compatibility with other MySQL Cluster management tools such as ndb_mgm.

    Note

    create cluster causes cluster node IDs to be assigned consecutively, in the order that the nodes are specified in the process_host_list.

    Each host referenced in the list must be part of the site for which the package used in create cluster is defined.

    For processes of types mysqld and ndbapi, the hostname is required, but not enforced in the running cluster. In other words, an [api] section is created in the cluster config.ini file, but no HostName parameter is specified; thus, the mysqld or ndbapi can connect from any host. (Currently, there is no way using MySQL Cluster Manager to specify that a mysqld or ndbapi process is restricted to connecting from a single host.)

  • A name for the cluster. Once the cluster has been created, this name is used to refer to it in other cluster management commands such as delete cluster, start cluster, stop cluster, and so forth. (For information about these commands, see the other subsections of Section 3.4, “MySQL Cluster Manager Cluster Commands”.) Like other object names used with MySQL Cluster Manager, the cluster_name must be valid according to the rules given elsewhere in this document for identifiers (see Chapter 3, MySQL Cluster Manager Client Commands).

  • MySQL Cluster Manager 1.1.4 and later supports an additional --verbose option for this command that causes create cluster to output extra information as it is executed, as shown later in this section.

For example, consider the following command issued in the MySQL Cluster Manager client, which creates a cluster named mycluster: 

mcm> create cluster --package=mypackage
  -> --processhosts=ndb_mgmd@flundra,ndbd@tonfisk,ndbd@grindval,mysqld@flundra
  -> mycluster;
+------------------------------+
| Command result               |
+------------------------------+
| Cluster created successfully |
+------------------------------+
1 row in set (7.71 sec)

As defined by the command just shown, mycluster consists of four nodes: a management node on host flundra; two data nodes—one on each of the hosts tonfisk and grindval; and one SQL node, also on host flundra.

Using the --verbose option causes the command to print output similar to that produced by the list processes command, as shown here: 

mcm> create cluster --verbose --package=mypackage
  -> --processhosts=ndb_mgmd@flundra,ndbd@tonfisk,ndbd@grindval,mysqld@flundra
  -> mycluster;
+--------+----------+----------+
| NodeId | Name     | Host     |
+--------+----------+----------+
| 49     | ndb_mgmd | flundra  |
| 1      | ndbd     | tonfisk  |
| 2      | ndbd     | grindval |
| 50     | mysqld   | flundra  |
+--------+----------+----------+
4 rows in set (0.32 sec)

You can also create this cluster in such a way that the mysqld process is permitted to connect to the cluster from any host able to reach the other cluster hosts over the network as shown here: 

mcm> create cluster --package=mypackage
  -> --processhosts=ndb_mgmd@flundra,ndbd@tonfisk,ndbd@grindval,mysqld@*
  -> mycluster;
+------------------------------+
| Command result               |
+------------------------------+
| Cluster created successfully |
+------------------------------+
1 row in set (7.71 sec)
Note

In the case of a “free” ndbapi process, it is not necessary to have the MySQL Cluster Manager software installed on the host where the ndbapi process is running.

Configuration changes to the newly-created cluster can be made using the set command prior to starting the cluster. This is often preferable to doing after the cluster has been started, since set commands used to make configuration changes in a running cluster can require a rolling restart, and rolling restarts of clusters having many nodes or large quantities of data (or both) may take a great deal of time to complete. For more information, see Section 3.5.2, “The set Command”.

Note

When creating a cluster having more than one mysqld process on the same host machine, MySQL Cluster Manager assigns the MySQL default port (3306) to each of them. Therefore, you must assign a unique port for each mysqld process in the cluster.

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