25.5.4 ndb_mgmd — NDB 集群管理服务器守护进程
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.
All options that can be used with ndb_mgmd are shown in the following table. Additional descriptions follow the table.
-
Command-Line Format --bind-address=host
Type String Default Value [none]
Causes the management server to bind to a specific network interface (host name or IP address). This option has no default value.
-
Command-Line Format --character-sets-dir=path
Directory containing character sets.
-
Command-Line Format --cluster-config-suffix=name
Type String Default Value [none]
Override defaults group suffix when reading cluster configuration sections in
my.cnf
; used in testing. -
Command-Line Format --config-cache[=TRUE|FALSE]
Type Boolean Default Value TRUE
This option, whose default value is
1
(orTRUE
, orON
), can be used to disable the management server's configuration cache, so that it reads its configuration fromconfig.ini
every time it starts (see Section 25.4.3, “NDB Cluster Configuration Files”). You can do this by starting the ndb_mgmd process with any one of the following options:-
--config-cache=0
-
--config-cache=FALSE
-
--config-cache=OFF
Using one of the options just listed is effective only if the management server has no stored configuration at the time it is started. If the management server finds any configuration cache files, then the
--config-cache
option or the--skip-config-cache
option is ignored. Therefore, to disable configuration caching, the option should be used the first time that the management server is started. Otherwise—that is, if you wish to disable configuration caching for a management server that has already created a configuration cache—you must stop the management server, delete any existing configuration cache files manually, then restart the management server with--skip-config-cache
(or with--config-cache
set equal to 0,OFF
, orFALSE
).Configuration cache files are normally created in a directory named
mysql-cluster
under the installation directory (unless this location has been overridden using the--configdir
option). Each time the management server updates its configuration data, it writes a new cache file. The files are named sequentially in order of creation using the following format:ndb_node-id_config.bin.seq-number
node-id
is the management server's node ID;seq-number
is a sequence number, beginning with 1. For example, if the management server's node ID is 5, then the first three configuration cache files would, when they are created, be namedndb_5_config.bin.1
,ndb_5_config.bin.2
, andndb_5_config.bin.3
.If your intent is to purge or reload the configuration cache without actually disabling caching, you should start ndb_mgmd with one of the options
--reload
or--initial
instead of--skip-config-cache
.To re-enable the configuration cache, simply restart the management server, but without the
--config-cache
or--skip-config-cache
option that was used previously to disable the configuration cache.ndb_mgmd does not check for the configuration directory (
--configdir
) or attempts to create one when--skip-config-cache
is used. (Bug #13428853) -
-
--config-file=
,filename
-f
filename
Command-Line Format --config-file=file
Disabled by skip-config-file
Type File name Default Value [none]
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.This option has no default value, and is ignored unless the management server is forced to read the configuration file, either because ndb_mgmd was started with the
--reload
or--initial
option, or because the management server could not find any configuration cache. If--config-file
is specified without either of--initial
or--reload
, ndb_mgmd refuses to start.The
--config-file
option is also read if ndb_mgmd was started with--config-cache=OFF
. See Section 25.4.3, “NDB Cluster Configuration Files”, for more information. -
Command-Line Format --configdir=directory
--config-dir=directory
Type File name Default Value $INSTALLDIR/mysql-cluster
Specifies the cluster management server's configuration cache directory. This must be an absolute path. Otherwise, the management server refuses to start.
--config-dir
is an alias for this option. -
Command-Line Format --connect-retries=#
Type Integer Default Value 12
Minimum Value 0
Maximum Value 12
Number of times to retry connection before giving up.
-
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.
-
Command-Line Format --connect-string=connection_string
Type String Default Value [none]
Same as --ndb-connectstring.
-
Command-Line Format --core-file
Write core file on error; used in debugging.
-
--daemon
,-d
Command-Line Format --daemon
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.
-
Command-Line Format --defaults-extra-file=path
Type String Default Value [none]
Read given file after global files are read.
-
Command-Line Format --defaults-file=path
Type String Default Value [none]
Read default options from given file only.
-
Command-Line Format --defaults-group-suffix=string
Type String Default Value [none]
Also read groups with concat(group, suffix).
-
Command-Line Format --help
Display help text and exit.
-
Command-Line Format --initial
Configuration data is cached internally, rather than being read from the cluster global configuration file each time the management server is started (see Section 25.4.3, “NDB Cluster Configuration Files”). Using the
--initial
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 cache. Second,--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.When a management server starts, it checks for another management server in the same NDB Cluster and tries to use the other management server's configuration data. This behavior has implications when performing a rolling restart of an NDB Cluster with multiple management nodes. See Section 25.6.5, “Performing a Rolling Restart of an NDB Cluster”, for more information.
When used together with the
--config-file
option, the cache is cleared only if the configuration file is actually found. -
Command-Line Format --install[=name]
Platform Specific Windows Type String Default Value ndb_mgmd
Causes ndb_mgmd to be installed as a Windows service. Optionally, you can specify a name for the service; if not set, the service name defaults to
ndb_mgmd
. Although it is preferable to specify other ndb_mgmd program options in amy.ini
ormy.cnf
configuration file, it is possible to use them together with--install
. However, in such cases, the--install
option must be specified first, before any other options are given, for the Windows service installation to succeed.It is generally not advisable to use this option together with the
--initial
option, since this causes the configuration cache to be wiped and rebuilt every time the service is stopped and started. Care should also be taken if you intend to use any other ndb_mgmd options that affect the starting of the management server, and you should make absolutely certain you fully understand and allow for any possible consequences of doing so.The
--install
option has no effect on non-Windows platforms. -
Command-Line Format --interactive
Starts ndb_mgmd in interactive mode; that is, an ndb_mgm client session is started as soon as the management server is running. This option does not start any other NDB Cluster nodes.
-
Command-Line Format --log-name=name
Type String Default Value MgmtSrvr
Provides a name to be used for this node in the cluster log.
-
Command-Line Format --login-path=path
Type String Default Value [none]
Read given path from login file.
-
Command-Line Format --no-login-paths
Skips reading options from the login path file.
-
Command-Line Format --mycnf
Read configuration data from the
my.cnf
file. -
Command-Line Format --ndb-connectstring=connection_string
Type String Default Value [none]
Set connection string. Syntax:
[nodeid=
. Overrides entries inid
;][host=]hostname
[:port
]NDB_CONNECTSTRING
andmy.cnf
. Ignored if--config-file
is specified; a warning is issued if both options are used concurrently. -
Command-Line Format --ndb-mgm-tls=level
Type Enumeration Default Value relaxed
Valid Values relaxed
strict
Sets the level of TLS support required to connect to the management server; one of
relaxed
orstrict
.relaxed
(the default) means that a TLS connection is attempted, but success is not required;strict
means that TLS is required to connect. -
Command-Line Format --ndb-mgmd-host=connection_string
Type String Default Value [none]
Same as --ndb-connectstring.
-
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. -
Command-Line Format --ndb-tls-search-path=list
Type Path name Default Value (Unix) $HOME/ndb-tls
Default Value (Windows) $HOMEDIR/ndb-tls
Specify a list of directories to search for a CA file. On Unix platforms, the directory names are separated by colons (
:
); on Windows systems, the semicolon character (;
) is used as the separator. A directory reference may be relative or absolute; it may contain one or more environment variables, each denoted by a prefixed dollar sign ($
), and expanded prior to use.Searching begins with the leftmost named directory and proceeds from left to right until a file is found. An empty string denotes an empty search path, which causes all searches to fail. A string consisting of a single dot (
.
) indicates that the search path limited to the current working directory.If no search path is supplied, the compiled-in default value is used. This value depends on the platform used: On Windows, this is
\ndb-tls
; on other platforms (including Linux), it is$HOME/ndb-tls
. This can be overridden by compiling NDB Cluster using-DWITH_NDB_TLS_SEARCH_PATH
. -
Command-Line Format --no-nodeid-checks
Do not perform any checks of node IDs.
-
Command-Line Format --nodaemon
Instructs ndb_mgmd not to start as a daemon process.
The default behavior for ndb_mgmd on Windows is to run in the foreground, making this option unnecessary on Windows platforms.
-
Command-Line Format --no-defaults
Do not read default options from any option file other than login file.
-
Command-Line Format --nowait-nodes=list
Type Numeric Default Value [none]
Minimum Value 1
Maximum Value 255
When starting an NDB Cluster is configured with two management nodes, 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, permitting 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 = 198.51.100.101 [ndbd] NodeId = 2 HostName = 198.51.100.102 [ndbd] NodeId = 3 HostName = 198.51.100.103 [ndbd] NodeId = 4 HostName = 198.51.100.104 [ndb_mgmd] NodeId = 10 HostName = 198.51.100.150 [ndb_mgmd] NodeId = 11 HostName = 198.51.100.151 [api] NodeId = 20 HostName = 198.51.100.200 [api] NodeId = 21 HostName = 198.51.100.201
Assume that you wish to start this cluster using only the management server having node ID
10
and running on the host having the IP address 198.51.100.150. (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 198.51.100.150 to enter the following command:$> ndb_mgmd --ndb-nodeid=10 --nowait-nodes=11
As shown in the preceding example, when using
--nowait-nodes
, you must also use the--ndb-nodeid
option to specify the node ID of this ndb_mgmd process.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 connection string that references both management servers, like this:
$> ndbd -c 198.51.100.150,198.51.100.151
The same is true with regard to the connection string used with any mysqld processes that you wish to start as NDB Cluster SQL nodes connected to this cluster. See Section 25.4.3.3, “NDB Cluster Connection Strings”, 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 to permit 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 NDB 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.
NoteWhen 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.
-
Command-Line Format --print-defaults
Print program argument list and exit.
-
Command-Line Format --print-full-config
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
--config-file
(-f
) option. -
Command-Line Format --reload
NDB Cluster configuration data is stored internally rather than being read from the cluster global configuration file each time the management server is started (see Section 25.4.3, “NDB 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 deleted. Second,--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
--reload
option is ignored.When
--reload
is used, the management server must be able to communicate with data nodes and any other management servers in the cluster before it attempts to read the global configuration file; otherwise, the management server fails to start. This can happen due to changes in the networking environment, such as new IP addresses for nodes or an altered firewall configuration. In such cases, you must use--initial
instead to force the existing cached configuration to be discarded and reloaded from the file. See Section 25.6.5, “Performing a Rolling Restart of an NDB Cluster”, for additional information. -
Command-Line Format --remove[=name]
Platform Specific Windows Type String Default Value ndb_mgmd
Remove a management server process that has been installed as a Windows service, optionally specifying the name of the service to be removed. Applies only to Windows platforms.
-
Command-Line Format --skip-config-file
Do not read cluster configuration file; ignore
--initial
and--reload
options if specified. -
Command-Line Format --usage
Display help text and exit; same as --help.
-
--verbose
,-v
Command-Line Format --verbose
Remove a management server process that has been installed as a Windows service, optionally specifying the name of the service to be removed. Applies only to Windows platforms.
-
Command-Line Format --version
Display version information and exit.
It is not strictly necessary to specify a connection string when starting the management server. However, if you are using more than one management server, a connection string should be provided and each node in the cluster should specify its node ID explicitly.
See Section 25.4.3.3, “NDB Cluster Connection Strings”, for information about using connection strings. Section 25.5.4, “ndb_mgmd — The NDB 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 25.4, “Configuration of NDB Cluster”, discusses how to set up this file. -
ndb_
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 25.6, “Management of NDB Cluster”.node_id
_cluster.logBy default, when the size of the cluster log reaches one million bytes, the file is renamed to
ndb_
, wherenode_id
_cluster.log.seq_id
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 number4
.) You can change the size and number of files, and other characteristics of the cluster log, using theLogDestination
configuration parameter. -
ndb_
is the file used fornode_id
_out.logstdout
andstderr
when running the management server as a daemon. -
ndb_
is the process ID file used when running the management server as a daemon.node_id
.pid