21.6.3.1 NDB Cluster Logging Management Commands

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.

Note

Events are reported per data node, and that the threshold can be set to different values on different nodes.

Table 21.48 Cluster log categories, with default threshold setting

Category	Default threshold (All data nodes)
STARTUP	7
SHUTDOWN	7
STATISTICS	7
CHECKPOINT	7
NODERESTART	7
CONNECTION	8
ERROR	15
INFO	7
BACKUP	15
CONGESTION	7
SCHEMA	7

The STATISTICS category can provide a great deal of useful data. See Section 21.6.3.3, “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.

Note

These correspond to Unix syslog levels, except for LOG_EMERG and LOG_NOTICE, which are not used or mapped.

Table 21.49 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.

Important

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.