MySQL 8.0 Reference Manual Including MySQL NDB Cluster 8.0
The ndb_mgm management client process is actually not needed to run the cluster. Its value lies in providing a set of commands for checking the cluster's status, starting backups, and performing other administrative functions. The management client accesses the management server using a C API. Advanced users can also employ this API for programming dedicated management processes to perform tasks similar to those performed by ndb_mgm.
To start the management client, it is necessary to supply the host name and port number of the management server:
shell> ndb_mgm [host_name [port_num]]
For example:
shell> ndb_mgm ndb_mgmd.mysql.com 1186
The default host name and port number are
localhost and 1186, respectively.
The following table includes options that are specific to the NDB Cluster management client program ndb_mgm. Additional descriptions follow the table. For options common to most NDB Cluster programs (including ndb_mgm), see Section 22.4.31, “Options Common to NDB Cluster Programs — Options Common to NDB Cluster Programs”.
Table 22.256 Command-line options for the ndb_mgm program
| Format | Description | Added, Deprecated, or Removed |
|---|---|---|
| Set number of times to retry connection before giving up; 0 means 1 attempt only (and no retries) | (Supported in all MySQL 8.0 based releases) |
|
| Set number of times to retry connection before giving up; synonym for --connect-retries | (Supported in all MySQL 8.0 based releases) |
|
| Execute command and exit | (Supported in all MySQL 8.0 based releases) |
| Property | Value |
|---|---|
| Command-Line Format | --connect-retries=# |
| Type | Numeric |
| Default Value | 3 |
| Minimum Value | 0 |
| Maximum Value | 4294967295 |
This option specifies the number of times following the
first attempt to retry a connection before giving up (the
client always tries the connection at least once). The
length of time to wait per attempt is set using
--connect-retry-delay.
This option is synonymous with the
--try-reconnect option,
which is now deprecated.
The default for this option this option differs from its
default when used with other NDB
programs. See
Section 22.4.31, “Options Common to NDB Cluster Programs — Options Common to NDB Cluster Programs”, for
more information.
| Property | Value |
|---|---|
| Command-Line Format | --execute=name |
This option can be used to send a command to the NDB Cluster
management client from the system shell. For example, either
of the following is equivalent to executing
SHOW in the management
client:
shell>ndb_mgm -e "SHOW"shell>ndb_mgm --execute="SHOW"
This is analogous to how the
--execute or
-e option works with the
mysql command-line client. See
Section 4.2.2.1, “Using Options on the Command Line”.
If the management client command to be passed using this option contains any space characters, then the command must be enclosed in quotation marks. Either single or double quotation marks may be used. If the management client command contains no space characters, the quotation marks are optional.
| Property | Value |
|---|---|
| Command-Line Format | --try-reconnect=# |
| Deprecated | Yes |
| Type | Numeric |
| Type | Integer |
| Default Value | 12 |
| Default Value | 3 |
| Minimum Value | 0 |
| Maximum Value | 4294967295 |
If the connection to the management server is broken, the
node tries to reconnect to it every 5 seconds until it
succeeds. By using this option, it is possible to limit the
number of attempts to number
before giving up and reporting an error instead.
This option is deprecated and subject to removal in a future
release. Use
--connect-retries, instead.
Additional information about using ndb_mgm can be found in Section 22.5.1, “Commands in the NDB Cluster Management Client”.