HP StoreEasy 3000 Gateway Storage - Manual (Page 89)

6 Cluster administration
One important feature of HP StorageWorks X3000 G2 Network Storage System models 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.
X3000 G2 Network Storage System User Guide 89