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Cluster Administration

203NAS 4000s and 9000s Administration Guide

For example, if from a client a network share map F: was established and assigned to

\\Node1\Eng1 instead of \\Fileserver1\Eng1, when Node1 fails and Node2 assumes ownership,

the map will become invalid because the reference in the map is to \\Node1. If the map were

created to the virtual name and Node1 were to fail, the map would still exist when the group

associated with Eng1 failed over to Node2.

The previous diagram is an example and is not intended to imply limitations of a single group

or node. Groups can contain multiple physical disks resources and file shares and nodes can

have multiple groups, as shown by the group owned by Node2.

Cluster Planning

Clustering the NAS 4000s or 9000s greatly enhances the availability of file service by enabling

file shares to fail over to additional NAS devices, if problems arise. Clients see only a brief

interruption of service as the file share resource transitions from one server node to the other.

Requirements for taking advantage of clustering include:

■ Storage planning

■ Network planning

■ Protocol planning

Storage Planning

For clustering, a storage unit (LUN) must be designated for the cluster and configured as a

mirrorset. This LUN is used for the Quorum disk. The Quorum disk is the shared storage used

by the cluster nodes to coordinate the internal cluster state.

One or more RAID arrays are dedicated to each cluster node for data storage. Each cluster

node will assume ownership of at least one physical disk resource. That owner node will serve

all shares within that physical disks resource, until a failover condition occurs. When a failover

occurs, the physical disk resource and all associated shares will transition over to the

remaining nodes and will remain there until the other node is returned to service. Some types

of shares are not cluster aware and will not be available during a failover condition. See the

“Protocol Planning” section for additional information.

To prepare a basic disk for use in a cluster, a cluster group for each basic disk should be

created to allow each resource to failover separately. Once the group is created, a physical disk

resource is created in each of the groups. Cluster groups may contain more than one physical

disk depending on the site-specific requirements. This physical disk resource is required for

basic disk to successfully work in a cluster environment protecting it from simultaneous access

from each node.

Note: The LUN underlying the basic disk should be presented to only one node of the cluster using

selective storage presentation SAN switch zoning or having only one node online at all times until

such times as the physical resource for the basic disk is established.

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HP 4000S Guia do Utilizador Página 203