Technical data

Transparent failover compensates only for a controller failure, and not
for failures of either the SCSI bus or host adapters and is therefore not a
NSPOF configuration.
______________________ Note _______________________
Set each controller to transparent failover mode before configuring
devices (SET FAILOVER COPY = THIS_CONTROLLER).
To achieve a NSPOF configuration, you need multiple-bus failover and two
shared SCSI buses.
You may use multiple-bus failover (SET MULTIBUS_FAILOVER COPY =
THIS_CONTROLLER) to help achieve a NSPOF configuration if each host has
two shared SCSI buses to the array controllers. One SCSI bus is connected
to one controller and the other SCSI bus is connected to the other controller.
Each member system has a host bus adapter for each shared SCSI bus. The
load can be distributed across the two controllers. In case of a host adapter
or SCSI bus failure, the host can redistribute the load to the surviving
controller. In case of a controller failure, the surviving controller will handle
all units.
______________________ Notes ______________________
Multiple-bus failover does not support device partitioning with
the HSZ70 or HSZ80.
Partitioned storagesets and partitioned single-disk units cannot
function in multiple-bus failover dual-redundant configurations.
Because they are not supported, you must delete your partitions
before configuring the HSZ70 or HSZ80 controllers for
multiple-bus failover.
Device partitioning is supported with HSG60 and HSG80 array
controllers with ACS Version 8.5.
Multiple-bus failover does not support tape drives or CD-ROM
drives.
RA3000
The RA3000 uses either active/active or active/passive mode and does not
support transparent or multiple-bus failover.
In the active/active mode, the top controller sees one host port as active,
while the other controller sees the other host port as active. The controllers
3–18 Shared SCSI Bus Requirements and Configurations Using UltraSCSI Hardware