Computer Not Reachable

Microsoft.SystemCenter.HealthService.ComputerDown (AggregateMonitor)

This monitor indicates if a computer can be pinged.

Knowledge Base article:

Summary

This unit monitor will generate a critical state on Heartbeat failure if the computer cannot be reached through an ICMP ping.

This is an indication that the target System Center Management Health Service on that computer has lost network connectivity to its parent Management Server.

Note that you will see 2 alerts when the computer is offline:

When the computer network connectivity is restored and the System Center Management Health Service starts to heartbeat, then both alerts will be automatically closed.

Causes

This can be caused by:

Resolutions

You can try the following to diagnose and remediate this issue:

Element properties:

TargetMicrosoft.SystemCenter.HealthServiceWatcher
Parent MonitorSystem.Health.AvailabilityState
AlgorithmWorstOf
CategoryStateCollection
EnabledTrue
Alert GenerateTrue
Alert SeverityError
Alert PriorityHigh
Alert Auto ResolveTrue
RemotableTrue
AccessibilityPublic
Alert Message
Failed to Connect to Computer
The computer {0} was not accessible.
Commentthis is aggregate monitor which has no contributors (that being regular unit monitors)

Source Code:

<AggregateMonitor ID="Microsoft.SystemCenter.HealthService.ComputerDown" Comment="this is aggregate monitor which has no contributors (that being regular unit monitors)" Accessibility="Public" Enabled="true" Target="SCLibrary!Microsoft.SystemCenter.HealthServiceWatcher" ParentMonitorID="Health!System.Health.AvailabilityState" Remotable="true" Priority="High">
<Category>StateCollection</Category>
<AlertSettings AlertMessage="Microsoft.SystemCenter.HealthService.ComputerDown.AlertMessage">
<AlertOnState>Error</AlertOnState>
<AutoResolve>true</AutoResolve>
<AlertPriority>High</AlertPriority>
<AlertSeverity>Error</AlertSeverity>
<AlertParameters>
<AlertParameter1>$Target/Property[Type="SCLibrary!Microsoft.SystemCenter.HealthServiceWatcher"]/HealthServiceName$</AlertParameter1>
</AlertParameters>
</AlertSettings>
<Algorithm>WorstOf</Algorithm>
</AggregateMonitor>