Health
Admin › Health shows whether the system is doing its job. It is open to people with the health right, and to everyone who can change settings.
Messages going out
For email, text messages and push notifications: whether each provider accepts the credentials it was given, how many messages wait in each queue, and who receives the alerts when delivery fails. The queues for notifications and for timed events show here too.
Uptime and incidents
Log an incident here: when it started and ended, and what happened. The monthly uptime figure is worked out from the incidents logged.
Server memory
This server's memory use since it last started, with the period it was measured over. A steady rise over hours is the sign to raise with support.