HP StorageWorks Clustered File System 3.6.0 Windows Storage Server Edition Administration Guide (403103-005, January 2008)

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Advanced Monitor Topics
The topics described here provide technical details about HP Clustered
File System operations. This information is not required to use HP
Clustered File System in typical configurations; however, it may be useful
if you want to design custom scripts and monitors, to integrate HP
Clustered File System with custom applications, or to diagnose complex
configuration problems.
The Effect of Monitors on Failover
Typically a virtual host has a primary network interface and one or more
backup interfaces. On the servers supplying the interfaces, the state of the
virtual host is either active or inactive.When HP Clustered File System
needs to fail over a virtual host, it looks for the healthiest backup server.
To make this determination, HP Clustered File System considers the state
of any service or device monitors associated with the virtual host.
Service Monitors
Service monitors are configured on a virtual host. The service to be
monitored is expected to be running simultaneously on the primary
server and on the backup servers associated with the virtual host. The
monitor uses a probe mechanism to determine whether the service is up.
The probe mechanism is in one of the following states on each server: Up,
Down, Unknown, Timeout.
A service monitor also has an activity status on each server. The status
can be one of the following: Starting, Active, Suspended, Stopping,
Inactive, Failure.