Specifications

2–8 Controller and Host Concepts
Figure 2–4. Example of Separate Host Port IDs in Multiple-Bus Failover
As Figure 2–4 shows, all ports on both controllers are active and have the ability to
present all LUNs, 0–199, to the host. If one pot or one path loses communication, the
drivers in the host can access the units through another port or another path.
Preferring the Host Path
In multiple-bus failover, the host can designate which controller initially accesses the
units. This is called preferring host paths. See “ADD UNIT,” page 7–27 and the
PREFERRED_PATH switch for details.
FC-SW
FC-SW
FC-SW
FC-SW
CXO6862A
Host
port 1
active
Controller A
Host
port 2
active
Controller B
Host
port 2
active
Host
port 1
active