OES Cluster Services for Open Enterprise Server (OES) is a multiple-node server clustering system that ensures high availability and manageability of critical network resources including data, applications, and services. It stores information in NetIQ eDirectory about the cluster and its resources. It supports failover, failback, and cluster migration of individually managed cluster resources. You can cluster migrate a resource to a different server in order to perform rolling cluster maintenance or to balance the resource load across member nodes.