Compaq AA-RHGWC-TE - Manual (Page 50)

• A maximum of three cascaded switches is supported, with a maximum of
two hops between switches. The maximum hop length is 10 km longwave
single-mode or 500 meters via shortwave multimode Fibre Channel cable.
• Tru64 UNIX Version 5.1 limits the number of Fibre Channel targets
to 126.
• Tru64 UNIX Version 5.1 allows up to 255 LUNs per target.
• The HSG60 and HSG80 supports transparent and multiple-bus failover
mode when used in a TruCluster Server Version 5.1 configuration.
Multiple-bus failover is recommended for high availability in a cluster.
• A storage array with dual-redundant HSG60 or HSG80 controllers in
transparent mode failover is two targets and consumes four ports on a
switch.
• A storage array with dual-redundant HSG60 or HSG80 controllers in
multiple-bus failover is four targets and consumes 4 ports on a switch.
• Each KGPSA is one target.
• The HSG60 and HSG80 documentation refers to the controllers as
Controllers A (top) and B (bottom). Each controller provides two ports
(left and right). (The HSG80 documentation refers to these ports as Port
1 and 2, respectively.) In transparent failover mode, only one left port
and one right port are active at any given time.
With transparent failover enabled, assuming that the left port of the top
controller and the right port of the bottom controller are active, if the top
controller fails in such a way that it can no longer properly communicate
with the switch, then its functions will automatically fail over to the
bottom controller (and vice versa).
• In transparent failover mode, you can configure which controller presents
each HSG60 or HSG80 storage element (unit) to the cluster. Ordinarily,
the left port of either controller serves the units designated D0 through
D99, and the right port serves those designated D100 through D199.
• In multiple-bus failover mode, all units (D0 through D199) are visible to
all host ports, but accessible only through one controller at any specific
time. The host can control the failover process by moving unit(s) from
one controller to the other controller.
2.3.2 KZPSA-BB SCSI Adapter Restrictions
KZPSA-BB SCSI adapters have the following restrictions:
• The KZPSA-BB requires A12 firmware.
• If you have a KZPSA-BB adapter installed in an AlphaServer that
supports the bus_probe_algorithm console variable (for example, the
2–8 Hardware Requirements and Restrictions