The Sun Cluster system makes the path between users and data highly available by using multihost disks, multipathing, and a cluster file system. The Sun Cluster system monitors failures for the following:
Applications – Most of the Sun Cluster data services supply a fault monitor that periodically probes the data service to determine its health. A fault monitor verifies that the application daemon or daemons are running and that clients are being served. Based on the information that is returned by probes, a predefined action such as restarting daemons or causing a failover can be initiated.
Disk Paths – Sun Cluster software supports disk-path monitoring (DPM). DPM improves the overall reliability of failover and switchover by reporting the failure of a secondary disk path.
Internet Protocol (IP) Multipath – Solaris IP network multipathing software on Sun Cluster systems provide the basic mechanism for monitoring public network adapters. IP multipathing also enables failover of IP addresses from one adapter to another adapter when a fault is detected.
Quorum Devices - Sun Cluster software supports quorum device monitoring by periodically testing that quorum works on quorum devices. When Sun Cluster software detects a failure, the Sun Cluster system reports the failure and marks the quorum device that is not working correctly. When the Sun Cluster system detects that a previously failed quorum device now operates correctly, the system automatically brings the quorum device back into service. Bringing the quorum device back into service includes placing the correct quorum reservation information on the device. The Sun Cluster system automatically monitors any configured quorum device that is not in maintenance mode, regardless of type.