Normally, RESTART  fails if taking the node offline would result in an incomplete cluster. The -f  option forces the node to restart without checking for this. If this option is used and the result is an incomplete cluster, the entire cluster is restarted. 

## • node_id  STATUS 

Displays status information for the data node identified by node_id  (or for all data nodes). 

The output from this command also indicates when the cluster is in single user mode. 

## • node_id  REPORT report-type 

Displays a report of type report-type  for the data node identified by node_id , or for all data nodes using ALL . 

Currently, there are three accepted values for report-type : 

• BackupStatus  provides a status report on a cluster backup in progress 

• MemoryUsage  displays how much data memory and index memory is being used by each data node as shown in this example: 

ndb_mgm> ALL REPORT MEMORY Node 1: Data usage is 5%(177 32K pages of total 3200) Node 1: Index usage is 0%(108 8K pages of total 12832) Node 2: Data usage is 5%(177 32K pages of total 3200) Node 2: Index usage is 0%(108 8K pages of total 12832) 

This information is also available from the ndbinfo.memoryusage  table. 

• EventLog  reports events from the event log buffers of one or more data nodes. 

report-type  is case-insensitive and “fuzzy” ; for MemoryUsage , you can use MEMORY  (as shown in the prior example), memory , or even simply MEM  (or mem ). You can abbreviate BackupStatus  in a similar fashion. 

## • ENTER SINGLE USER MODE node_id 

Enters single user mode, whereby only the MySQL server identified by the node ID node_id  is permitted to access the database. 

Beginning with NDB 8.0.17, the ndb_mgm  client provides a clear acknowledgement that this command has been issued and has taken effect, as shown here: 

ndb_mgm> ENTER SINGLE USER MODE 100 Single user mode entered Access is granted for API node 100 only. 

Also in NDB 8.0.17 and later, the API or SQL node having exclusive access when in single user mode is indicated in the output of the SHOW  command, like this: 

ndb_mgm> SHOW Cluster Configuration --------------------- [ndbd(NDB)] 2 node(s) id=5 @127.0.0.1 (mysql-8.0.17 ndb-8.0.17, single user mode, Nodegroup: 0, *) id=6 @127.0.0.1 (mysql-8.0.17 ndb-8.0.17, single user mode, Nodegroup: 0) [ndb_mgmd(MGM)] 1 node(s) 

