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Primary Array
Controller
Standby Array
Controller
Standby
Storage Hub
Primary
Storage Hub
Primary
Host Controller
Standby
Host Controller
Primary Path
Backup Path
Figure 4. Redundant Fibre Channel Loop
As the figure shows, a redundant data path is configured between the cluster servers and the
Compaq RAID Array 4000. The redundant components operate initially in standby mode. If any
component (host controller, storage hub, array controller, or cable) in the primary path fails, the
primary path becomes inactive, the standby path becomes active, and data transmission continues
without interruption over the standby path.
Cluster Interconnects
The cluster interconnect is a data path over which nodes of a cluster communicate. This type of
communication is termed intra-cluster communication. The ProLiant Cluster for NetWare 4.2
uses the standard public network controller card (NetWare Link), an optional Dedicated Link, and
the Fibre Channel Disk Link to implement intra-cluster communication. At a minimum, the
interconnect consists of two network adapters (one in each server) and a cable connecting the
adapters to a public network hub to be utilized as the NetWare Link.
The cluster nodes use the interconnect data path to:
•
Communicate cluster status
•
Send and receive heartbeat
Since Novell High Availability Server does not mirror data between servers, the transfer of the
heartbeat is very small (just the heartbeat or information about the health of the other server in the
cluster is sent over the links).
IMPORTANT: NHAS 1.0 requires IPX as the cluster communication protocol for the Direct
Link connection.
