In addition to the central configuration file, a cluster may also be controlled through a command-line interface available through the management client ndb_mgm. This is the primary administrative interface to a running cluster.
Commands for the event logs are given in Section 15.5.5, “Event Reports Generated in MySQL Cluster”; commands for creating backups and restoring from them are provided in Section 15.5.3, “Online Backup of MySQL Cluster”.
The management client has the following basic commands. In the
listing that follows,
either a database node ID or the keyword
which indicates that the command should be applied to all of the
cluster's data nodes.
Displays information on all available commands.
Displays information on the cluster's status.
In a cluster where multiple management nodes are in use, this command displays information only for data nodes that are actually connected to the current management server.
Brings online the data node identified by
node_id (or all data nodes).
Stops the data node identified by
node_id (or all data nodes). A data
node affected by this command disconnects from the cluster,
and its associated ndbd process terminates.
node_id RESTART [-n] [-i]
Restarts the data node identified by
node_id (or all data nodes).
-i option with
RESTART causes the data node to perform an
initial restart; that is, the node's file system is deleted
and recreated. The effect is the same as that obtained from
stopping the data node process and then starting it again
using ndbd --initial from the system shell.
-n option causes the data node
process to be restarted, but the data node is not actually
brought online until the appropriate
command is issued. The effect of this option is the same as
that obtained from stopping the data node and then starting it
ndbd --nostart or
-n from the system shell.
-a causes all current transactions
relying on this node to be aborted. No GCP check is done when
the node rejoins the cluster.
Displays status information for the data node identified by
node_id (or for all data nodes).
ENTER SINGLE USER MODE
Enters single user mode, whereby only the MySQL server
identified by the node ID
is permitted to access the database.
Do not attempt to have data nodes join the cluster while it is running in single user mode. Doing so can cause subsequent multiple node failures. (See Bug #20395 for more information.)
EXIT SINGLE USER MODE
Exits single user mode, enabling all SQL nodes (that is, all running mysqld processes) to access the database.
It is possible to use
EXIT SINGLE USER
MODE even when not in single user mode, although
the command has no effect in this case.
Terminates the management client.
This command does not affect any nodes connected to the cluster.
Shuts down all cluster data nodes and management nodes. To
exit the management client after this has been done, use
This command does not shut down any SQL nodes or API nodes that are connected to the cluster.