HP XP Racks - Manual (Page 165)

You can define paths between a single server host and multiple LUs. The figure shows that each
of the two hosts in the host group hg-lnx can access the three LUs.
You can also define paths between multiple server hosts and a single LU. The figure shows that
the LU identified by the LDKC:CU:LDEV number 00:00:00 is accessible from the two hosts that
belong to the hg-lnx host group.
The figure also shows that the LUs associated with the hg-lnx host group are addressed by
numbers 0000 to 0002. The address number of an LU is referred to as a LUN (logical unit number).
When Continuous Access Synchronous and other software manipulates LUs, the software use LUNs
to specify the LUs to be manipulated.
You can add, change, and delete LU paths when the system is in operation. For example, if new
disks or server hosts are added to your storage system, you can add new LU paths. If an existing
server host is to be replaced, you can delete the LU paths that correspond to the host before
replacing the host. You do not need to restart the system when you add, change, or delete LU
paths.
If a hardware failure (such as a CHA failure) occurs, there is a chance that some LU paths are
disabled and some I/O operations are stopped. To avoid such a situation, you can define alternate
LU paths; if one LU path fails, the alternate path takes over the host I/O. For information, see
“Defining LU paths” (page 177) and “Defining alternate LU paths” (page 179) .
LUN Manager license requirements
Use of LUN Manager on the HP XP7 Storage requires the following:
•
A license key for LUN Manager software.
LUN Manager rules, restrictions, and guidelines
Rules
•
In a fibre channel environment, up to 2,048 LU paths can be defined for one host group and
up to 2,048 LU paths can be defined for one port.
•
Up to 255 host groups can be created for one fibre channel port.
LUN Manager overview 165