Cluster nodes are generally attached to one or more disks. Nodes not attached to disks use the cluster file system to access the multihost disks. Nodes in parallel database configurations share concurrent access to some or all disks.
Every node in the cluster is aware when another node joins or leaves the cluster. Also, every node in the cluster is aware of the resources that are running locally as well as the resources that are running on the other cluster nodes.
Nodes in the same cluster should have similar processing, memory, and I/O capability to enable failover to occur without significant degradation in performance. Because of the possibility of failover, each node should have sufficient capacity to meet service level agreements if a node fails.