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About igroups

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Initiator groups (igroups) are tables of FC protocol host WWPNs or iSCSI host node names. You can define igroups and map them to LUNs to control which initiators have access to LUNs.

Typically, you want all of the host's initiator ports or software initiators to have access to a LUN. If you are using multipathing software or have clustered hosts, each initiator port or software initiator of each clustered host needs redundant paths to the same LUN.

You can create igroups that specify which initiators have access to the LUNs either before or after you create LUNs, but you must create igroups before you can map a LUN to an igroup.

Initiator groups can have multiple initiators, and multiple igroups can have the same initiator. However, you cannot map a LUN to multiple igroups that have the same initiator. An initiator cannot be a member of igroups of differing ostypes.

Example of how igroups give LUN access

You can create multiple igroups to define which LUNs are available to your hosts. For example, if you have a host cluster, you can use igroups to ensure that specific LUNs are visible to only one host in the cluster or to all of the hosts in the cluster.

The following table illustrates how four igroups give access to the LUNs for four different hosts that are accessing the storage system. The clustered hosts (Host3 and Host4) are both members of the same igroup (group3) and can access the LUNs mapped to this igroup. The igroup named group4 contains the WWPNs of Host4 to store local information that is not intended to be seen by its partner.

Hosts with HBA WWPNs, IQNs, or EUIs igroups WWPNs, IQNs, EUIs added to igroups LUNs mapped to igroups

Host1, single-path (iSCSI software initiator)

iqn.1991-05.com.microsoft:host1

group1

iqn.1991-05.com.microsoft:host1

/vol/vol2/lun1

Host2, multipath (two HBAs)

10:00:00:00:c9:2b:6b:3c

10:00:00:00:c9:2b:02:3c

group2

10:00:00:00:c9:2b:6b:3c

10:00:00:00:c9:2b:02:3c

/vol/vol2/lun2

Host3, multipath, clustered with host 4

10:00:00:00:c9:2b:32:1b

10:00:00:00:c9:2b:41:02

group3

10:00:00:00:c9:2b:32:1b

10:00:00:00:c9:2b:41:02

10:00:00:00:c9:2b:51:2c

10:00:00:00:c9:2b:47:a2

/vol/vol2/qtree1/lun3

Host4, multipath, clustered (not visible to Host3)

10:00:00:00:c9:2b:51:2c

10:00:00:00:c9:2b:47:a2

group4

10:00:00:00:c9:2b:51:2c

10:00:00:00:c9:2b:47:a2

/vol/vol2/qtree2/lun4 /vol/vol2/qtree1/lun5