Google provides three methods of informing users of service disruptions or outages; Alerts, Apps Status Dashboard, Enterprise Support Center
We highly recommend that admins turn on alerts in your Google Admin console for service disruptions or outages. This will send an email regarding the disruption to your administrators as soon as there is an known issue with the Google Apps services.
1. Login to admin.google.com
2. Navigate to Reports > Manage Reports
3. Enable "Apps outage alert"
Apps Status Dashboard
This will show the outage and any additional information regarding the issue at http://www.google.com/appsstatus
Enterprise Support Center
The Known Issues Page of the Enterprise Support Center will also display any known issues and the status of the investigation.