4.1.0 HP PolyServe Matrix Server administration guide (T5392-96073, October 2010)

17 Advanced monitor topics
The topics described here provide technical details about Matrix Server monitor
operations. This information is not required to use Matrix Server in typical
configurations; however, it may be useful if you want to design custom scripts and
monitors, to integrate Matrix Server with custom applications, or to diagnose complex
configuration problems.
The effect of monitors on virtual host failover
Typically a virtual host has a primary network interface and one or more backup
network interfaces. On the servers supplying the interfaces, the state of the virtual
host is either active or inactive.
When Matrix Server needs to fail over a virtual host, it looks for the healthiest backup
server. To make this determination, Matrix Server 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.
The following examples show state transitions for a service monitor that uses the
default values for autorecovery, priority, and serial script ordering. Start and Stop
scripts are also defined for the monitor. The virtual host associated with the monitor
has a primary interface and two backup interfaces.
The first example shows the state transitions that occur at startup from an unknown
state. At i1, all instances of the monitor have completed stopping. At i2, the virtual
HP PolyServe Matrix Server 4.1.0 administration guide 233