Sun Cluster system makes all components on the ”path” between users and data highly available by monitoring the applications themselves, the file system, and network interfaces.
The Sun Cluster software detects a node failure quickly and creates an equivalent server for the resources on the failed node. The Sun Cluster software ensures that resources unaffected by the failed node are constantly available during the recovery and that resources of the failed node become available as soon as they are recovered.
Each Sun Cluster data service supplies 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 returned by probes, predefined actions such as restarting daemons or causing a failover, can be initiated.
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. You can use one of two methods for monitoring disk paths. The first method is provided by the cldevice command. This command enables you to monitor, unmonitor, or display the status of disk paths in your cluster. See the cldevice(1CL) man page for more information about command-line options.
The second method for monitoring disk paths in your cluster is provided by the Sun Cluster Manager graphical user interface (GUI). Sun Cluster Manager provides a topological view of the monitored disk paths. The view is updated every 10 minutes to provide information about the number of failed pings.
Each Solaris host in a cluster has its own IP network multipathing configuration, which can differ from the configuration on other hosts in the cluster. IP network multipathing monitors the following network communication failures:
The transmit and receive path of the network adapter has stopped transmitting packets.
The attachment of the network adapter to the link is down.
The port on the switch does not transmit or receive packets.
The physical interface in a group is not present at system boot.
Sun Cluster software supports the monitoring of quorum devices. Periodically, each node in the cluster tests the ability of the local node to work correctly with each configured quorum device that has a configured path to the local node and is not in maintenance mode. This test consists of an attempt to read the quorum keys on the quorum device.
When the Sun Cluster system discovers that a formerly healthy quorum device has failed, the system automatically marks the quorum device as unhealthy. When the Sun Cluster system discovers that a formerly unhealthy quorum device is now healthy, the system marks the quorum device as healthy and places the appropriate quorum information on the quorum device.
The Sun Cluster system generates reports when the health status of a quorum device changes. When nodes reconfigure, an unhealthy quorum device cannot contribute votes to membership. Consequently, the cluster might not continue to operate.