The Blackouts page states whether a target is under blackout, that is, if a target is scheduled for maintenance or if the target maintenance (and hence the blackout) is in progress.
On the Blackouts page:
You can access status and availability information about the target.
If the target is a host, you can view all the blacked out targets for that host.
From this page, you can view all blackouts that are scheduled for this target, including those that have been scheduled by other administrators.
To determine when the blackout ends, click the target's name. The target's home page appears. Click the Blackouts link in the Related Links section. The information will state when the blackout will end.
Note: Blackout periods are excluded from calculating the target's availability percentage.
Introduction to Managing Alerts
Understanding Alert Information on Home Pages
Enterprise Manager Information Roadmap
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