25.5.31 ndb_waiter — Wait for NDB Cluster to Reach a Given Status

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MySQL 8.4 Reference Manual Including MySQL NDB Cluster 8.4

25.5.31 ndb_waiter — Wait for NDB Cluster to Reach a Given Status

ndb_waiter repeatedly (each 100 milliseconds) prints out the status of all cluster data nodes until either the cluster reaches a given status or the --timeout limit is exceeded, then exits. By default, it waits for the cluster to achieve STARTED status, in which all nodes have started and connected to the cluster. This can be overridden using the --no-contact and --not-started options.

The node states reported by this utility are as follows:

• NO_CONTACT: The node cannot be contacted.
• UNKNOWN: The node can be contacted, but its status is not yet known. Usually, this means that the node has received a START or RESTART command from the management server, but has not yet acted on it.
• NOT_STARTED: The node has stopped, but remains in contact with the cluster. This is seen when restarting the node using the management client's RESTART command.
• STARTING: The node's ndbd process has started, but the node has not yet joined the cluster.
• STARTED: The node is operational, and has joined the cluster.
• SHUTTING_DOWN: The node is shutting down.
• SINGLE USER MODE: This is shown for all cluster data nodes when the cluster is in single user mode.

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

Usage

ndb_waiter [-c connection_string]

Additional Options

• --character-sets-dir

Directory containing character sets. - --connect-retries

Number of times to retry connection before giving up. - --connect-retry-delay

Number of seconds to wait between attempts to contact management server. - --connect-string

Same as --ndb-connectstring. - --core-file

Write core file on error; used in debugging. - --defaults-extra-file

Read given file after global files are read. - --defaults-file

Read default options from given file only. - --defaults-group-suffix

Also read groups with concat(group, suffix). - --login-path

Read given path from login file. - --no-login-paths

Skips reading options from the login path file. - --help

Display help text and exit. - --ndb-connectstring

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

Sets the level of TLS support required to connect to the management server; one of relaxed or strict. relaxed (the default) means that a TLS connection is attempted, but success is not required; strict means that TLS is required to connect. - --ndb-mgmd-host

Same as --ndb-connectstring. - --ndb-nodeid

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

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

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. - --no-contact, -n

Instead of waiting for the STARTED state, ndb_waiter continues running until the cluster reaches NO_CONTACT status before exiting. - --no-defaults

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

Instead of waiting for the STARTED state, ndb_waiter continues running until the cluster reaches NOT_STARTED status before exiting. - --nowait-nodes=list

When this option is used, ndb_waiter does not wait for the nodes whose IDs are listed. The list is comma-delimited; ranges can be indicated by dashes, as shown here:

$> ndb_waiter --nowait-nodes=1,3,7-9

Important

Do not use this option together with the --wait-nodes option. - --print-defaults

Print program argument list and exit. - --timeout=seconds, -t seconds

Time to wait. The program exits if the desired state is not achieved within this number of seconds. The default is 120 seconds (1200 reporting cycles). - --single-user

The program waits for the cluster to enter single user mode. - --usage

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

Controls verbosity level of printout. Possible levels and their effects are listed here:

• 0: Do not print (return exit code only; see following for exit codes).
• 1: Print final connection status only.

• 2: Print status each time it is checked.

  This is the same behavior as in versions of NDB Cluster previous to 8.4.

Exit codes returned by ndb_waiter are listed here, with their meanings:

• 0: Success.
• 1: Wait timed out.
• 2: Parameter error, such as an invalid node ID.
• 3: Failed to connect to the management server.
• --version

Display version information and exit. - --wait-nodes=list, -w list

When this option is used, ndb_waiter waits only for the nodes whose IDs are listed. The list is comma-delimited; ranges can be indicated by dashes, as shown here:

$> ndb_waiter --wait-nodes=2,4-6,10

Important

Do not use this option together with the --nowait-nodes option.

Sample Output. Shown here is the output from ndb_waiter when run against a 4-node cluster in which two nodes have been shut down and then started again manually. Duplicate reports (indicated by ...) are omitted.

$> ./ndb_waiter -c localhost

Connecting to mgmsrv at (localhost)
State node 1 STARTED
State node 2 NO_CONTACT
State node 3 STARTED
State node 4 NO_CONTACT
Waiting for cluster enter state STARTED

...

State node 1 STARTED
State node 2 UNKNOWN
State node 3 STARTED
State node 4 NO_CONTACT
Waiting for cluster enter state STARTED

...

State node 1 STARTED
State node 2 STARTING
State node 3 STARTED
State node 4 NO_CONTACT
Waiting for cluster enter state STARTED

...

State node 1 STARTED
State node 2 STARTING
State node 3 STARTED
State node 4 UNKNOWN
Waiting for cluster enter state STARTED

...

State node 1 STARTED
State node 2 STARTING
State node 3 STARTED
State node 4 STARTING
Waiting for cluster enter state STARTED

...

State node 1 STARTED
State node 2 STARTED
State node 3 STARTED
State node 4 STARTING
Waiting for cluster enter state STARTED

...

State node 1 STARTED
State node 2 STARTED
State node 3 STARTED
State node 4 STARTED
Waiting for cluster enter state STARTED

Note

If no connection string is specified, then ndb_waiter tries to connect to a management on localhost, and reports Connecting to mgmsrv at (null).