HP StorageWorks 8000 NAS - Manual (Page 26)

24 NAS 8000 Concepts
Understanding High Availability
Note This section applies only if you have purchased a high-
availability NAS solution.
High availability characterizes a system that is designed to avoid the loss of
service by reducing or managing failures and minimizing downtime. High
availability implies a service level in which both planned and unplanned
downtime is minimized.
Cluster Components
The HP NAS 8000 cluster consists of two NAS servers, a Quorum server and
storage that may come from either a direct-attached configuration or a SAN.
The NAS servers share access to the storage and provide failover capabilities
for each other, but function as independent servers. The main purpose of
high-availability clusters is to provide a higher degree of storage availability
to client systems than is possible with a single server. This is accomplished by
minimizing single points of failure and providing functional redundancy.
Server downtime and interruptions to storage availability are minimized by
failing over file serving capabilities between the NAS servers in the event of a
failure in either server.