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
CLUSTERLOGcategory
=threshold
Logs
category
events with priority less than or equal tothreshold
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 25.26 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 25.6.3.3, “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.
These correspond to Unix syslog
levels,
except for LOG_EMERG
and
LOG_NOTICE
, which are not used or mapped.
Table 25.27 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.