Relationship of WWPNs and iSCSI names for host objects

A host can be created with worldwide port names (WWPNs) or iSCSI names. The WWPN name space and the iSCSI name space within the system share the same internal system resources.

The iSCSI name in a host object can take up to a maximum equivalent of four WWPNs depending on the number of I/O groups in which the host participates. This affects the maximum number of hosts that you can configure in a system.

Each system I/O group can have up to 512 WWPN entries. Each system I/O group can have up to 256 iSCSI IQNs.

Creating an iSCSI host object with one iSCSI name in one I/O group is equivalent to creating a Fibre Channel host with one WWPN.
Creating an iSCSI host object with two iSCSI names in one I/O group is equivalent to creating a Fibre Channel host object with two WWPNs.
Creating an iSCSI host object with one iSCSI name in two I/O groups is equivalent to creating a Fibre Channel host object with two WWPNs in each I/O group, which reduces the number of host objects that can be created.

By default, host objects are created across all I/O groups. For each host created with the default parameters, the equivalent of four WWPNs is used in all I/O groups. This results in a maximum of 128 iSCSI host objects per clustered system, when the default options are always used.

To create iSCSI host objects in fewer I/O groups, run the following command, which creates a host with one iSCSI name in I/O groups 0 and 1:

mkhost -iscsiname iscsi1 -iogrp 0:1

Host (and other system) limits are described here:

http://www-01.ibm.com/support/docview.wss?uid=ssg1S1004368