Resource configuration planning

Resources in a Linux HA cluster include the application and all the shared file systems that belong to it. Linux HA provides a highly available environment by identifying a set of cluster-wide resources essential to uninterrupted processing, and then defining relationships among nodes that ensure these resources are available to client processes. When a cluster node fails or detaches from the cluster for a scheduled outage, the Cluster Manager redistributes its resources among any number of the surviving nodes.

Linux HA considers the following as resource types:

  • Volume Groups
  • Disks
  • File Systems
  • File Systems to be NFS mounted
  • File Systems to be NFS exported
  • Service IP addresses
  • Applications

Each resource in a cluster is defined as part of a resource group. This allows you to combine related resources that need to be together to provide a particular service. A resource group also includes the list of nodes that can acquire those resources and serve them to clients. Resources can either be cascading or rotating.