Server Generated Alerts
For sending alerts pushed to a third party
tool or paging software, subscribe to alert_que with the
dbms_aqadm.add_subscriber procedure. Use the
enable_db_access procedure to associate a database user with
the subscribing agent. Optionally, an asynchronous notification
can be received by enqueing alerts using alert_que.
Subscribers will have to de-enqueue the message metadata to get
the content. For enqueue notifications through email or HTTP
posts, configure the database server through dbms_aqelm
with information on mail server or proxy server.
How are Alerts Recorded by AWR?
Background processes periodically flush the
data to the Automatic Workload Repository. Thus the AWR captures
a history of metric values. The alert history table and
alert_que are automatically purged
periodically by the system.
The tablespace alert feature is currently
coded to wake up every 10 minutes and check for tablespace
related alerts. Currently there is no way to change this
behavior without changing the code. The 10-minute interval is
only specific to the tablespace alerts, other alerts can have
different values. For example, if the alert is matrix based,
then the interval can be set to every one minute since MMON
collects metrics every
minute and will
compare them to their thresholds.
In order to set and view the threshold
values using Enterprise Manager, do the following steps:
-
Invoke OEM and connect to the
database.
-
On the Home page, click on the
Manage Metrics link at the bottom of the page.
Figure 4.1 - Manage Metrics
