21.5.5 ndb_mgm — The NDB Cluster Management Client

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:

$> ndb_mgm [host_name [port_num]]

For example:

$> ndb_mgm ndb_mgmd.mysql.com 1186

The default host name and port number are localhost and 1186, respectively.

Options that can be used with ndb_mgm are shown in the following table. Additional descriptions follow the table.

Table 21.25 Command-line options used with the program ndb_mgm

Format	Description	Added, Deprecated, or Removed
--character-sets-dir=path	Directory containing character sets	(Supported in all NDB releases based on MySQL 5.7)
--connect-retry-delay=#	Number of seconds to wait between attempts to contact management server	(Supported in all NDB releases based on MySQL 5.7)
--connect-string=connection_string, -c connection_string	Same as --ndb-connectstring	(Supported in all NDB releases based on MySQL 5.7)
--core-file	Write core file on error; used in debugging	(Supported in all NDB releases based on MySQL 5.7)
--defaults-extra-file=path	Read given file after global files are read	(Supported in all NDB releases based on MySQL 5.7)
--defaults-file=path	Read default options from given file only	(Supported in all NDB releases based on MySQL 5.7)
--defaults-group-suffix=string	Also read groups with concat(group, suffix)	(Supported in all NDB releases based on MySQL 5.7)
--execute=command, -e command	Execute command and exit	(Supported in all NDB releases based on MySQL 5.7)
--help, -?	Display help text and exit	(Supported in all NDB releases based on MySQL 5.7)
--login-path=path	Read given path from login file	(Supported in all NDB releases based on MySQL 5.7)
--ndb-connectstring=connection_string, -c connection_string	Set connect string for connecting to ndb_mgmd. Syntax: "[nodeid=id;][host=]hostname[:port]". Overrides entries in NDB_CONNECTSTRING and my.cnf	(Supported in all NDB releases based on MySQL 5.7)
--ndb-mgmd-host=connection_string, -c connection_string	Same as --ndb-connectstring	(Supported in all NDB releases based on MySQL 5.7)
--ndb-nodeid=#	Set node ID for this node, overriding any ID set by --ndb-connectstring	(Supported in all NDB releases based on MySQL 5.7)
--ndb-optimized-node-selection	Enable optimizations for selection of nodes for transactions. Enabled by default; use --skip-ndb-optimized-node-selection to disable	(Supported in all NDB releases based on MySQL 5.7)
--no-defaults	Do not read default options from any option file other than login file	(Supported in all NDB releases based on MySQL 5.7)
--print-defaults	Print program argument list and exit	(Supported in all NDB releases based on MySQL 5.7)
--try-reconnect=#, -t #	Set number of times to retry connection before giving up; synonym for --connect-retries	(Supported in all NDB releases based on MySQL 5.7)
--usage, -?	Display help text and exit; same as --help	(Supported in all NDB releases based on MySQL 5.7)
--version, -V	Display version information and exit	(Supported in all NDB releases based on MySQL 5.7)

• --character-sets-dir

  Command-Line Format	--character-sets-dir=path

  Directory containing character sets.

• --connect-retries=#

  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.

• --connect-retry-delay

  Command-Line Format	--connect-retry-delay=#
  Type	Integer
  Default Value	5
  Minimum Value	0
  Maximum Value	5

  Number of seconds to wait between attempts to contact management server.

• --connect-string

  Command-Line Format	--connect-string=connection_string
  Type	String
  Default Value	[none]

  Same as --ndb-connectstring.

• --core-file

  Command-Line Format	--core-file

  Write core file on error; used in debugging.

• --defaults-extra-file

  Command-Line Format	--defaults-extra-file=path
  Type	String
  Default Value	[none]

  Read given file after global files are read.

• --defaults-file

  Command-Line Format	--defaults-file=path
  Type	String
  Default Value	[none]

  Read default options from given file only.

• --defaults-group-suffix

  Command-Line Format	--defaults-group-suffix=string
  Type	String
  Default Value	[none]

  Also read groups with concat(group, suffix).

• --execute=command, -e command

  Command-Line Format	--execute=command

  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:

  $> ndb_mgm -e "SHOW"
  
  $> 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”.

  Note

  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.

• --help

  Command-Line Format	--help

  Display help text and exit.

• --login-path

  Command-Line Format	--login-path=path
  Type	String
  Default Value	[none]

  Read given path from login file.

• --ndb-connectstring

  Command-Line Format	--ndb-connectstring=connection_string
  Type	String
  Default Value	[none]

  Set connect string for connecting to ndb_mgmd. Syntax: [nodeid=id;][host=]hostname[:port]. Overrides entries in NDB_CONNECTSTRING and my.cnf.

• --ndb-mgmd-host

  Command-Line Format	--ndb-mgmd-host=connection_string
  Type	String
  Default Value	[none]

  Same as --ndb-connectstring.

• --ndb-nodeid

  Command-Line Format	--ndb-nodeid=#
  Type	Integer
  Default Value	[none]

  Set node ID for this node, overriding any ID set by --ndb-connectstring.

• --ndb-optimized-node-selection

  Command-Line Format	--ndb-optimized-node-selection

  Enable optimizations for selection of nodes for transactions. Enabled by default; use --skip-ndb-optimized-node-selection to disable.

• --no-defaults

  Command-Line Format	--no-defaults

  Do not read default options from any option file other than login file.

• --print-defaults

  Command-Line Format	--print-defaults

  Print program argument list and exit.

• --try-reconnect=number

  Command-Line Format	--try-reconnect=#
  Deprecated	Yes
  Type (≥ 5.7.10-ndb-7.5.0)	Numeric
  Type	Integer
  Default Value (≥ 5.7.10-ndb-7.5.0)	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.

• --usage

  Command-Line Format	--usage

  Display help text and exit; same as --help.

• --version

  Command-Line Format	--version

  Display version information and exit.

Additional information about using ndb_mgm can be found in Section 21.6.1, “Commands in the NDB Cluster Management Client”.