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 17.4.23, “Options Common to MySQL Cluster Programs”.
Table 17.10. ndb_mgmd Command Line Options
|--bind-address||Local bind address||5.1.22-ndb-6.3.2|
|-c||Specify the cluster configuration file; in NDB-6.4.0 and later, needs --reload or --initial to override configuration cache if present|
|--configdir=directory||Specify the cluster management server's configuration cache directory||5.1.30-ndb-6.4.0|
|--daemon||Run ndb_mgmd in daemon mode (default)|
|--initial||Causes the management server reload its configuration data from the configuration file, bypassing the configuration cache||5.1.30-ndb-6.4.0|
|--interactive||Run ndb_mgmd in interactive mode (not officially supported in production; for testing purposes only)|
|--log-name=||A name to use when writing messages applying to this node in the cluster log.||5.1.37-ndb-7.0.8|
|--mycnf||Read cluster configuration data from the my.cnf file|
|--no-nodeid-checks||Do not provide any node id checks|
|--nodaemon||Do not run ndb_mgmd as a daemon|
|--nowait-nodes=list||Do not wait for these management nodes when starting this management server. Also requires --ndb-nodeid to be used.||5.1.39-ndb-7.1.0|
|--print-full-config||Print full configuration and exit|
|--reload||Causes the management server to compare the configuration file with its configuration cache||5.1.30-ndb-6.4.0|
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:
port is not specified,
the management client attempts to use port 1186.
This option was added in MySQL Cluster NDB 6.2.5 and MySQL Cluster NDB 6.3.2.
Beginning with MySQL Cluster NDB 6.4.0, 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”). This option
instructs the management server to its configuration cache
directory indicated. By
default, this is a directory named
mysql-cluster in the MySQL
installation directory — for example, if you compile
and install MySQL Cluster on a Unix system using the
default location, this is
This behavior can be overridden using the
option for ndb_mgmd. Each of these
options is described elsewhere in this section.
This option is available beginning with MySQL Cluster NDB 6.4.0.
Beginning with MySQL Cluster NDB 7.0.8,
--config-dir is accepted as an alias for
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.
Beginning with MySQL Cluster NDB 6.4.0, this option is
ignored unless the management server is forced to read the
configuration file, either because
ndb_mgmd was started with the
option, or because the management server could not find
any configuration cache. See
Section 17.3.2, “MySQL Cluster Configuration Files”, for more
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.
Beginning with MySQL Cluster NDB 6.4.0, 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 this 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
--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.
This option was introduced in MySQL Cluster NDB 6.4.0.
Provides a name to be used for this node in the cluster log.
This option was added in MySQL Cluster NDB 7.0.8.
Instructs ndb_mgmd not to start as a daemon process.
As of MySQL Cluster NDB 7.0.8, the default behavior for ndb_mgmd on Windows is to run in the foreground, making this option unnecessary on Windows platforms. (Bug#45588)
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
Beginning with MySQL Cluster NDB 6.4.0, 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
--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
option is ignored.
This option was introduced in MySQL Cluster NDB 6.4.0.
When starting a MySQL Cluster is configured with two management nodes and running MySQL Cluster NDB 7.0 and later, 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, allowing 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 [mgm] NodeId = 10 HostName = 192.168.0.150 [mgm] 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
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:
ndb_mgmd --ndb-nodeid=10 --nowait-nodes=11
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:
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 220.127.116.11, “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
in MySQL Cluster NDB 7.0 and later) to allow 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.
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.
This option was introduced in MySQL Cluster NDB 7.0.10.
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 18.104.22.168, “The MySQL Cluster Connectstring”, for information about using connectstrings. Section 17.4.4, “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.
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
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
is the file used for
stderr when running the management
server as a daemon.
is the process ID file used when running the management
server as a daemon.