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

10.11
Exporting Virtual Volumes
InForm OS Version 2.3.1 3PAR InForm OS Concepts Guide
■ Understanding which virtual copies become stale if the administration space is full and the
copy-on-write data cannot be written. A stale snapshot is one that cannot be completely
recreated because the most recent changes will not be included. The current snapshot and
all its children become stale when a write fails. For example, if there is no space to write the
copy-on-write data when a host writes to S1_0, then S1_0, S1_0_1, and S1_0_0 become
stale.
10.5 Exporting Virtual Volumes
Virtual volumes are the only data layer component visible to hosts. You export a virtual volume
to make it available to one or more hosts by creating an association between the volume and a
logical unit number (LUN). The characteristics of this association are defined when you create a
Virtual Volume-LUN pairing (VLUN). A VLUN is a pairing between a virtual volume and a LUN
expressed as either a VLUN template or an active VLUN.
Exporting virtual volumes can be performed with both the 3PAR InForm Command Line
Interface (CLI) and the 3PAR InForm Management Console. Refer to the 3PAR InForm OS CLI
Administrator’s Manual and the 3PAR InForm Management Console Online Help for
instructions on how to perform this task.
10.5.1 VLUN Templates and Active VLUNs
A VLUN template sets up an association between a virtual volume and a LUN-host, LUN-port,
or LUN-host-port combination by establishing the export rule, or the manner in which the
volume is exported. When you create a VLUN template, if the current system state meets the
conditions established by the VLUN template, that template is immediately applied to create
one or more active VLUNs. These active VLUNs enable virtual volumes to be exported to hosts.
If the current system state does not meet the conditions of the VLUN template, no active
VLUNs are created until the conditions of the template are met.
Once a VLUN template is applied to create one or more active VLUNs, hosts continue to be able
to access volumes based on the export rule established by that template. Removing VLUNs
associated with a volume halts host access to that volume. Removing all VLUNs for a host stops
the host from accessing all volumes.
10.5.2 VLUN Template Types
A VLUN template sets up an association between a virtual volume and a LUN-host, LUN-port,
or LUN-host-port combination by establishing the export rule, or the manner in which the
volume is exported. A VLUN template enables the export of a virtual volume as a VLUN to a