ndb_mgm supports a number of management commands related to the cluster log and node logs. In the listing that follows, node_id denotes either a storage node ID or the keyword ALL, which indicates that the command should be applied to all of the cluster's data nodes.
CLUSTERLOG ON
Turns the cluster log on.
CLUSTERLOG OFF
Turns the cluster log off.
CLUSTERLOG INFO
Provides information about cluster log settings.
node_id CLUSTERLOG category=threshold
Logs category events with priority less than or equal to threshold in the cluster log.
CLUSTERLOG FILTER severity_level
Toggles cluster logging of events of the specified severity_level.
The following table describes the default setting (for all data nodes) of the cluster log category threshold. If an event has a priority with a value lower than or equal to the priority threshold, it is reported in the cluster log.
Events are reported per data node, and that the threshold can be set to different values on different nodes.
Table 23.53 Cluster log categories, with default threshold setting
| Category | Default threshold (All data nodes) |
|---|---|
STARTUP | 7 |
SHUTDOWN | 7 |
STATISTICS | 7 |
CHECKPOINT | 7 |
NODERESTART | 7 |
CONNECTION | 7 |
ERROR | 15 |
INFO | 7 |
The STATISTICS category can provide a great deal of useful data. See Section 23.5.3.3, “Using CLUSTERLOG STATISTICS in the NDB Cluster Management Client”, for more information.
Thresholds are used to filter events within each category. For example, a STARTUP event with a priority of 3 is not logged unless the threshold for STARTUP is set to 3 or higher. Only events with priority 3 or lower are sent if the threshold is 3.
The following table shows the event severity levels.
These correspond to Unix syslog levels, except for LOG_EMERG and LOG_NOTICE, which are not used or mapped.
Table 23.54 Event severity levels
| Severity Level Value | Severity | Description |
|---|---|---|
| 1 | ALERT | A condition that should be corrected immediately, such as a corrupted system database |
| 2 | CRITICAL | Critical conditions, such as device errors or insufficient resources |
| 3 | ERROR | Conditions that should be corrected, such as configuration errors |
| 4 | WARNING | Conditions that are not errors, but that might require special handling |
| 5 | INFO | Informational messages |
| 6 | DEBUG | Debugging messages used for NDBCLUSTER
development |
Event severity levels can be turned on or off (using CLUSTERLOG FILTER—see above). If a severity level is turned on, then all events with a priority less than or equal to the category thresholds are logged. If the severity level is turned off then no events belonging to that severity level are logged.
Cluster log levels are set on a per ndb_mgmd, per subscriber basis. This means that, in an NDB Cluster with multiple management servers, using a CLUSTERLOG command in an instance of ndb_mgm connected to one management server affects only logs generated by that management server but not by any of the others. This also means that, should one of the management servers be restarted, only logs generated by that management server are affected by the resetting of log levels caused by the restart.