HP StorageWorks HSG80 ACS Solution Software V8.8 for Sun Solaris Installation and Configuration Guide (AA-RV1RA-TE, March 2005)

Planning a Subsystem
46 HSG80 ACS Solution Software V8.8 for Sun Solaris Installation and Configuration Guide
If no value is specified for offset, then connections on port 1 have a default offset
of 0 and connections on port 2 have a default offset of 100.
For example, if all host connections use the default offset values, unit D2 will be
presented to a port 1 host connection as LUN 2 (unit number of 2 minus offset of
0). Unit D102 will be presented to a port 2 host connection as LUN 2 (unit number
of D102 minus offset of 100).
Figure 15 shows how units are presented as different LUNs, depending on the
offset of the host. In this illustration, host connection 1 and host connection 2
would need to be on host port 1; host connection 3 would need to be on host port
2.
Figure 15: LUN presentation to hosts, as determined by offset
Offsets other than the default values can be specified. For example, unit D17
would be visible to a host connection on port 1 that had an offset of 10 as LUN 7
(unit number of 17 minus offset of 10). The unit would not be visible to a host
connection with a unit offset of 18 or greater, because that offset is not within the
unit’s range (unit number of 17 minus offset of 18 is a negative number).
Similarly, unit D127 would be visible to a host connection on port 2 that had an
offset of 120 as LUN 7 (unit number of 127 minus offset of 120). The unit would
not be visible to a host connection with a unit offset of 128 or greater, because that
offset is not within the unit’s range (unit number of 127 minus offset of 128 is a
negative number).
Controller
units
Host
connection 1
Offset: 0
Host
connection 2
Offset: 20
Host
connection 3
Offset: 100
LUN 0
LUN 1
LUN 2
LUN 3
LUN 20
LUN 21
LUN 0
LUN 1
LUN 0
LUN 1
LUN 2
LUN 30
LUN 31
D0
D1
D2
D3
D20
D21
D100
D101
D102
D130
D131
CXO6455B