HP Array Controller HSG V8.7 Software - Manual (Page 106)

3–28 HSG80 User’s Guide
Assigning Unit Numbers for Host Access to Storagesets
You will need to assign a unit number to each storageset, single disk
unit, or storage device that you want your host to know about in your
subsystem. The host uses these numbers to indicate the source or target
for every I/O request it sends to a controller.
Each unit number contains the following:
n A letter that indicates the kind of devices in the storage unit. For
example, D for disk drives; P for passthrough devices (i.e. tape
drives, loaders, and libraries).
n A number from 0-199.
Assigning Unit Numbers in Transparent Failover Mode
Each controller has two ports, Port 1 and Port 2, as shown in Figure
3–10. There is a set number of units that are accessible, depending on
the host operating system. This maximum is a limitation of the host.
In transparent failover mode, the range of assignable units is 0-99 on
Port 1, and 100-199 on Port 2, regardless of what unit offset is set on
the host. In other words, all hosts on Port 2 have a unit offset of 100.
Do not split partitioned storagesets across ports; they must be on the
same port.
See Appendix B, “CLI Commands,” for details about the ADD UNIT
command.
Figure 3–10 Controller Port ID and Unit Numbers in Transparent
Failover Mode
Controller A
Port 1 (Primary)
Units 0-99
Port 2 (Standby)
Units 100-199
Controller B
Port 1 (Standby)
Units 0-99
Port 2 (Primary)
Units 100-199
CXO6187A