HP Surestore Disk Array 12h and FC60 - Manual (Page 115)

Topologies for HP-UX 115
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High Availability Topology
The high availability topology increases the availability of the single system distance
topology by protecting against single points of HP Fibre Channel-AL Hub failure with the
use of redundant HP Fibre Channel-AL Hubs connected to each other. Adding a second HP
Fibre Channel-AL Hub also increases the number of hosts and disk arrays that can be
connected to a single Fibre Channel-AL.
Each instance of the high availability topology uses the following hardware components:
• Two to four host systems or servers
• Two Fibre Channel I/O adapters per host
• Two 10-port HP Fibre Channel-AL Hubs
• Two controller modules per disk array
• Maximum of six dual-controller module disk arrays in a four-host Fibre Channel-AL or
Maximum of eight dual-controller module disk arrays in a two-host Fibre Channel-AL
• Maximum 500 m fibre optic cable distance on each connection between each host and
HP Fibre Channel-AL Hub and between each HP Fibre Channel-AL Hub and disk array,
for a total Fibre Channel-AL cable length not to exceed 5000 m
As its name implies, the high availability topology supports only dual-controller module
disk arrays (
Figure 39 ). The objective of this topology is to use redundant hardware
components to provide high availability, so disk arrays with single controller modules are
not supported. All hardware components and paths are redundant. If any hardware failure
occurs, I/O communication between host and disk array can be completed through another
path.
In this topology each host uses two Fibre Channel I/O adapters and each disk array uses
dual controller modules. One adapter in each host and one controller module in each disk
array connect to one HP Fibre Channel-AL Hub, forming one Fibre Channel-AL. The second
adapter in each host and the second controller module in each disk array connect to the
second HP Fibre Channel-AL Hub, cabled into a separate Fibre Channel-AL. This creates
two redundant Fibre Channel-ALs.