Compaq Parallel Database Cluster Model PDC/O2000 for Oracle8i and Windows 2000 Administrator Guide

Cluster Architecture 2-47
I/O Path Configuration Guidelines for
Redundant Fibre Channel Arbitrated
Loops
You can use either of two I/O path configurations for every redundant FC-AL
in your PDC/O2000 cluster:
■ Active/standby configuration
■ Active/active configuration
In every redundant FC-AL, at least two Fibre Host Adapters must be installed
in each node (one Fibre Host Adapter for each Storage Hub or FC-AL Switch
in that redundant FC-AL).
In the active/standby configuration, only one of the two Fibre Host Adapters in
each node is active at any one time; the other Fibre Host Adapter is in the
standby state. The active Fibre Host Adapter is connected to the first Storage
Hub or FC-AL Switch, which is connected to the active array controller in
each RA4000/RA4100 Array. The standby Fibre Host Adapter is connected to
the second Storage Hub or FC-AL Switch, which is connected to the standby
array controller in each RA4000/RA4100 Array. The standby Fibre Host
Adapter remains in the standby state unless a failover from the active I/O path
occurs. In the active/standby configuration, the failure of any component along
an active I/O path (Fibre Host Adapter, Storage Hub or FC-AL Switch, active
array controller, or Fibre Channel cable) causes Secure Path to implement a
complete failover to the components on the standby I/O path.
In the active/active configuration, both Fibre Host Adapters in each node are
simultaneously active. Both are active because each Fibre Host Adapter is
connected to a Storage Hub or FC-AL Switch that, in turn, is connected to an
active array controller in each RA4000/RA4100 Array. Because each Fibre
Host Adapter and Storage Hub or FC-AL Switch must connect to at least one
active array controller, at least two RA4000/RA4100 Arrays must be present
in an active/active configuration.