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6 Cluster administration
One important feature of HP StoreEasy 3000 Storage systems is that they can operate as a single
node or as a cluster. This chapter discusses cluster installation and cluster management issues.
Cluster overview
A failover cluster is a group of independent computers that work together to increase the availability
of applications and services. The clustered servers (called nodes) are connected by physical cables
and by software. If one of the cluster nodes fails, another node begins to provide service (a process
known as failover). Users experience a minimum of disruptions in service.
Up to eight server nodes can be connected to each other and deployed as a no single point of
failure (NSPOF) cluster. Utilizing a private network allows communication amongst themselves in
order to track the state of each cluster node. Each node sends out periodic messages to the other
nodes; these messages are called heartbeats. If a node stops sending heartbeats, the cluster service
fails over any resources that the node owns to another node. For example, if the node that owns
the Quorum disk is shut down for any reason, its heartbeat stops. The other nodes detect the lack
of the heartbeat and another node takes over ownership of the Quorum disk and the cluster.
Clustering servers greatly enhances the availability of file serving by enabling file shares to fail
over to additional storage systems if problems arise. Clients see only a brief interruption of service
as the file share resource transitions from one server node to the other.
Figure 24 Storage system cluster diagram
Cluster terms and components
Nodes
The most basic parts of a cluster are the servers, referred to as nodes. A server node is any individual
server in a cluster, or a member of the cluster.
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Cluster administration
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