ndbinfo: The NDB Cluster Information Database id=1 @10.100.10.1 (8.0.26-ndb-8.0.26, Nodegroup: 0, *) id=2 @10.100.10.2 (8.0.26-ndb-8.0.26, Nodegroup: 0) [ndb_mgmd(MGM)] 1 node(s) id=10 @10.100.10.10 (8.0.26-ndb-8.0.26) [mysqld(API)] 2 node(s) id=20 @10.100.10.20 (8.0.26-ndb-8.0.26) id=21 @10.100.10.21 (8.0.26-ndb-8.0.26) mysql>  SELECT node_id, remote_node_id, status -> FROM ndbinfo.transporters; +---------+----------------+---------------+ | node_id | remote_node_id | status | +---------+----------------+---------------+ | 1 | 1 | DISCONNECTED | | 1 | 2 | CONNECTED | | 1 | 10 | CONNECTED | | 1 | 20 | CONNECTED | | 1 | 21 | CONNECTED | | 2 | 1 | CONNECTED | | 2 | 2 | DISCONNECTED | | 2 | 10 | CONNECTED | | 2 | 20 | CONNECTED | | 2 | 21 | CONNECTED | +---------+----------------+---------------+ 10 rows in set (0.04 sec) mysql>  SELECT node_id, remote_node_id, status -> FROM ndbinfo.transporters; +---------+----------------+---------------+ | node_id | remote_node_id | status | +---------+----------------+---------------+ | 1 | 1 | DISCONNECTED | | 1 | 2 | CONNECTING | | 1 | 10 | CONNECTED | | 1 | 20 | CONNECTED | | 1 | 21 | CONNECTED | +---------+----------------+---------------+ 5 rows in set (0.02 sec) There are 10 rows in the  transporters  table—5 for the first data node, and 5 for the second—assuming that all data nodes are running, as shown here: If you shut down one of the data nodes in this cluster using the command  2 STOP  in the  ndb_mgm  client, then repeat the previous query (again using the  mysql  client), this table now shows only 5 rows—1 row for each connection from the remaining management node to another node, including both itself and the data node that is currently offline—and displays  CONNECTING  for the status of each remaining connection to the data node that is currently offline, as shown here: The  connect_count ,  overloaded ,  overload_count ,  slowdown , and  slowdown_count  counters are reset on connection, and retain their values after the remote node disconnects. The  bytes_sent and  bytes_received  counters are also reset on connection, and so retain their values following disconnection (until the next connection resets them). The  overload  state referred to by the  overloaded  and  overload_count  columns occurs when this transporter’s send buffer contains more than  OVerloadLimit  bytes (default is 80% of SendBufferMemory , that is, 0.8 * 2097152 = 1677721 bytes). When a given transporter is in a state of overload, any new transaction that tries to use this transporter fails with Error 1218 ( Send Buffers overloaded in NDB kernel ). This affects both scans and primary key operations. The  slowdown  state referenced by the  slowdown  and  slowdown_count  columns of this table occurs when the transporter’s send buffer contains more than 60% of the overload limit (equal to 0.6 * 2097152 = 4593