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Resources
Hardware and software components that are managed by the cluster service are called cluster
resources. Cluster resources have three defining characteristics:
They can be brought online and taken offline.
They can be managed in a cluster.
They can be owned by only one node at a time.
Examples of cluster resources are IP addresses, network names, physical disk resources, and file
shares. Resources represent individual system components. These resources are organized into
groups and managed as a group. Some resources are created automatically by the system and
other resources must be set up manually. Resource types include:
IP address resource
Cluster name resource
Cluster quorum disk resource
Physical disk resource
Virtual server name resources
SMB file share resources
NFS file share resources
FTP file share resources
iSCSI resources
Cluster groups
Cluster resources are placed together in cluster groups. Groups are the basic unit of failover
between nodes. Resources do not fail over individually; they fail over with the group in which they
are contained.
Virtual servers
A virtual server is a cluster group that consists of a static IP Address resource and a Network Name
resource. Several virtual servers can be created. By assigning ownership of the virtual servers to
the different server nodes, the processing load on the storage systems can be distributed between
the nodes of a cluster.
The creation of a virtual server allows resources dependent on the virtual server to fail over and
fail back between the cluster nodes. Cluster resources are assigned to the virtual server to ensure
non-disruptive service of the resources to the clients.
Failover and failback
Failover of cluster groups and resources happens:
When a node hosting the group becomes inactive.
When all of the resources within the group are dependent on one resource, and that resource
fails.
When an administrator forces a failover.
A resource and all of its dependencies must be located in the same group so that if a resource
fails over, all of its dependent resources fail over.
When a resource is failed over, the cluster service performs certain procedures. First, all of the
resources are taken offline in an order defined by the resource dependencies. Secondly, the cluster
Cluster terms and components
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