By default, the fault monitor monitors all logical volumes in the device group that the resource represents. If you require only a subset of the logical volumes in a device group to be monitored, set the LogicalDeviceList extension property.
The status of the device group is derived from the statuses of the individual logical volumes that are monitored. If all monitored logical volumes are healthy, the device group is healthy. If any monitored logical volume is faulty, the device group is faulty. If a device group is discovered to be faulty, monitoring of the resource that represents the group is stopped and the resource is put into the disabled state.
The status of an individual logical volume is obtained by querying the volume's volume manager. If the status of a Solaris Volume Manager for Sun Cluster volume cannot be determined from a query, the fault monitor performs file input/output (I/O) operations to determine the status.
For mirrored disks, if one submirror is faulty, the device group is still considered to be healthy.
If reconfiguration of userland cluster membership causes an I/O error, the monitoring of device group resources by fault monitors is suspended while userland cluster membership monitor (UCMM) reconfigurations are in progress.