HP 3PAR InForm OS 3.1.1 Concepts Guide

• Port presents allows any host on a specific port to see the volume.
• Matched set allows only a specific host on a specific port to see the volume.
Host Sees
A host sees VLUN template allows only a particular host connected to any port to see a virtual
volume. The system makes the virtual volume visible as a LUN to all the host’s WWNs, regardless
of which controller node port the WWNs appear on. If the host has more than one WWN, active
VLUNs are created for each host WWN. However, for any single host, there can only be one host
sees VLUN template for a given LUN.
If a WWN is added to an existing host definition, all virtual volumes that are exported to the host
using the host-sees VLUN template are exported to the new WWN. However, WWNs cannot be
removed from a host definition if a LUN is exported to the host.
Host Set
A host set VLUN template allows any host that is a member of the host set to see a volume. The
system makes the virtual volume visible as a LUN to all the members of the host set. Any hosts
added to the host set automatically see the VLUN, provided there are no conflicting LUN IDs. If
the added host has an exported LUN ID in the LUN ID range of the host set, the host cannot see
the LUN and must be assigned a new ID. If a host is removed from a host set, the removed host
loses all rights of the host set and cannot access volumes exported to the host set.
Port Presents
A port presents VLUN template allows any host connected to a particular port to see a virtual
volume. The system makes the virtual volume visible as a LUN to any of the host’s WWNs that
appear on the controller node port. As long as the VLUN template remains on the system, additional
active VLUNs are created when the port is attached to additional hosts. However, there can only
be one port presents VLUN template per port LUN combination.
The same virtual volume can be exported as different LUNs on the same or different ports.
CAUTION: If the system is operating in Common Criteria mode, there may be security risks with
port presents. For more information about Common Criteria, see the HP 3PAR InForm OS Common
Criteria Administrator’s Reference.
Matched Set
A matched set VLUN template is a combination of the host sees and port presents template types.
A matched set VLUN allows a particular host on a specified port to see a virtual volume. For any
single LUN, there can only be one matched set VLUN template with the same host-port combination.
50 Virtual Volumes