Compaq StorageWorks HSG60 ACS Solution Software V8.6 for Sun Solaris Installation and Configuration Guide

Planning a Subsystem 1–5
to take over for the active one. If one controller fails, its companion controller (known as
the surviving controller) takes control by making both its host ports active, as shown in
Figure 1–4.
Units are divided between the host ports:
■ Units 0-99 are on host port 1 of both controllers (but accessible only through the active
port).
■ Units 100-199 are on host port 2 of both controllers (but accessible only through the
active port).
The limitation of transparent failover is that it only compensates for a controller failure,
and not for failures of either the Fibre Channel link or host Fibre Channel adapters.
Figure 1–3. Transparent failover−normal operation
CXO7036A
CXO7036A
Host
port 1
active
Host
port 2
active
D100 D101 D120D0 D1
Host 1
Switch or hub
Host 2
Switch or hub
Host 3
Controller A
Controller B
Host
port 2
standby
Host
port 1
standby