3PAR InForm® OS 2.3.1 Concepts Guide (320-200112 Rev B, February 2010)

10.12
Exporting Virtual Volumes
3PAR InForm OS Concepts Guide InForm OS Version 2.3.1
host or hosts. Those volume exports, which are seen as LUNs by the host or hosts, are active
VLUNs.
A VLUN template can be one of the following types:
Host sees allows only a specific host to see a volume.
Host set allows any host that is a member of the host set to see a volume.
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.
10.5.2.1 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.
10.5.2.2 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 privileges of the host set and cannot access volumes exported to the host set.
10.5.2.3 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.