Commands in the NDB Cluster Management Client mysqld  exposes the NDB API statistics counters as system status variables, which can be identified from the prefix common to all of their names ( Ndb_api_ ). The values of these variables can be read in the mysql  client from the output of a  SHOW STATUS  statement, or by querying either the Performance Schema session_status  or  global_status  table. By comparing the values of the status variables before and after the execution of an SQL statement that acts on  NDB  tables, you can observe the actions taken on the NDB API level that correspond to this statement, which can be beneficial for monitoring and performance tuning of NDB Cluster. MySQL Cluster Manager provides an advanced command-line interface that simplifies many otherwise complex NDB Cluster management tasks, such as starting, stopping, or restarting an NDB Cluster with a large number of nodes. The MySQL Cluster Manager client also supports commands for getting and setting the values of most node configuration parameters as well as  mysqld  server options and variables relating to NDB Cluster. MySQL Cluster Manager version 1.4.8 provides experimental support for NDB 8.0. See MySQL™ Cluster Manager 1.4.8 User Manual, for more information. 23.5.1 Commands in the NDB Cluster Management Client 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 23.5.3, “Event Reports Generated in NDB Cluster” ; commands for creating backups and restoring from them are provided in Section 23.5.8, “Online Backup of NDB Cluster” . Using ndb_mgm with MySQL Cluster Manager.  MySQL Cluster Manager 1.4.8 provides expermental support for NDB 8.0. MySQL Cluster Manager handles starting and stopping processes and tracks their states internally, so it is not necessary to use  ndb_mgm  for these tasks for an NDB Cluster that is under MySQL Cluster Manager control. It is recommended  not  to use the  ndb_mgm  command-line client that comes with the NDB Cluster distribution to perform operations that involve starting or stopping nodes. These include but are not limited to the  START ,  STOP ,  RESTART , and  SHUTDOWN  commands. For more information, see MySQL Cluster Manager Process Commands. The management client has the following basic commands. In the listing that follows,  node_id  denotes either a data node ID or the keyword  ALL , which indicates that the command should be applied to all of the cluster’s data nodes. • HELP • CONNECT  connection-string Displays information on all available commands. Connects to the management server indicated by the connection string. If the client is already connected to this server, the client reconnects. Displays information on the cluster’s status. Possible node status values include  UNKNOWN , NO_CONTACT ,  NOT_STARTED ,  STARTING ,  STARTED ,  SHUTTING_DOWN , and  RESTARTING . The output from this command also indicates when the cluster is in single user mode (status  SINGLE USER MODE ). In NDB 8.0.17 and later, it also indicates which API or SQL node has exclusive access when this mode is in effect; this works only when all data nodes and management nodes connected to the cluster are version 8.0.17 or later. • SHOW • node_id  START 4439