HP XP P9500 Storage - Manual (Page 314)

When you select multiple host groups to which different host modes are defined, if the host group
assigned to an initiator port is included, you cannot finish the Edit Host Groups operation.
Description Item
Specify the name of the host group. Host Group name
Host group name can be up to 64 single-byte ASCII characters
(alpha-numerals and symbols).
You cannot use the following symbols: \ / : , ; * ? " < > |
You cannot use blanks at the beginning or end of the host group name.
If a host group assigned to an initiator port is included in the specified host
groups, this item is unavailable.
Select the host mode from the list. Host Mode
If a host group assigned to an initiator port is included in the specified host
groups, this item is unavailable.
314 LUN Manager GUI reference