17.4.24. ndb_waiter — Wait for MySQL 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.

The following table includes options that are specific to the MySQL Cluster native backup restoration program ndb_waiter. Additional descriptions follow the table. For options common to most MySQL Cluster programs (including ndb_waiter), see Section 17.4.25, "Options Common to MySQL Cluster Programs — Options Common to MySQL Cluster Programs".

Table 17.28. ndb_waiter Options and Variables: MySQL Cluster NDB7.3

Format	Description	Added / Removed
`--no-contact`, `-n`	Wait for cluster to reach NO CONTACT state	All MySQL 5.6 based releases
`--not-started`	Wait for cluster to reach NOT STARTED state	All MySQL 5.6 based releases
`--single-user`	Wait for cluster to enter single user mode	All MySQL 5.6 based releases
`--timeout=#`, `-t`	Wait this many seconds, then exit whether or not cluster has reached desired state; default is 2 minutes (120 seconds)	All MySQL 5.6 based releases
`--nowait-nodes=list`	List of nodes not to be waited for.	All MySQL 5.6 based releases
`--wait-nodes=list`, `-w`	List of nodes to be waited for.	All MySQL 5.6 based releases

Usage

ndb_waiter [-c connect_string]

Additional Options

--no-contact, -n

Instead of waiting for the STARTED state, ndb_waiter continues running until the cluster reaches NO_CONTACT status before exiting.
--not-started

Instead of waiting for the STARTED state, ndb_waiter continues running until the cluster reaches NOT_STARTED status before exiting.
--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.
--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:
```
shell> ndb_waiter
                    --nowait-nodes=1,3,7-9
```
Important

Do not use this option together with the --wait-nodes option.
--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:
```
shell> 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.

shell> ./ndb_waiter -c localhostConnecting to mgmsrv at (localhost)State node 1 STARTEDState node 2 NO_CONTACTState node 3 STARTEDState node 4 NO_CONTACTWaiting for cluster enter state STARTED...State node 1 STARTEDState node 2 UNKNOWNState node 3 STARTEDState node 4 NO_CONTACTWaiting for cluster enter state STARTED...State node 1 STARTEDState node 2 STARTINGState node 3 STARTEDState node 4 NO_CONTACTWaiting for cluster enter state STARTED...State node 1 STARTEDState node 2 STARTINGState node 3 STARTEDState node 4 UNKNOWNWaiting for cluster enter state STARTED...State node 1 STARTEDState node 2 STARTINGState node 3 STARTEDState node 4 STARTINGWaiting for cluster enter state STARTED...State node 1 STARTEDState node 2 STARTEDState node 3 STARTEDState node 4 STARTINGWaiting for cluster enter state STARTED...State node 1 STARTEDState node 2 STARTEDState node 3 STARTEDState node 4 STARTEDWaiting for cluster enter state STARTEDNDBT_ProgramExit: 0 - OK

Note

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