HP 3PAR StoreServ Concepts Guide: HP 3PAR OS 3.1.3

Thinly-provisioned Virtual Volumes
A TPVV is a volume that uses LDs that belong to a CPG. TPVVs associated with the same CPG
draw space from the LD pool as needed, allocating space on demand in 16 KB increments. As
the volumes that draw space from the CPG require additional storage, the HP 3PAR OS automatically
creates additional LDs and adds them to the pool until the CPG reaches the user-defined growth
limit which restricts the CPG maximum size. The TPVV volume size limit is 16 TB. For more
information about TPVVs, see “Thinly-Provisioned Virtual Volumes” (page 45).
NOTE: Creating TPVVs requires the HP 3PAR Thin Provisioning Software license. For more
information, see “HP 3PAR Software” (page 10).
Physical Copies
A physical copy is a full copy of a volume. The data in a physical copy is static; it is not updated
with subsequent changes to the parent volume. The parent volume is the original volume that is
copied to the destination volume. The parent volume can be a base volume, volume set, virtual
copy, or physical copy. Creating physical copies does not require a separate license.
A physical copy can be created only from a parent volume with enough free space to accommodate
writes to that volume during the physical copy operation. Physical copies can be online physical
copies or offline physical copies. For online physical copies, the destination volume is automatically
created and can be exported immediately. Offline physical copies require a destination volume
that must have a user space size at least as large as the user space of the base volume being
copied, and offline physical copies cannot be exported.
For additional information about physical copies, see “Physical Copies” (page 47).
Virtual Copy Snapshots
A snapshot is a virtual copy of a base volume. The base volume is the original volume that is
copied. Unlike a physical copy, which is a duplicate of an entire volume, a virtual copy only
records changes to the base volume. This allows an earlier state of the original virtual volume to
be recreated by starting with the current state of the virtual copy and rolling back all the changes
that have been made since the virtual copy was created.
You can make snapshots of: FPVVs, TPVVs, physical copies, or another virtual copy snapshot.
Snapshots are created by using copy-on-write techniques available only with the HP 3PAR Virtual
Copy Software license. Thousands of snapshots of each virtual volume can be created assuming
that there is sufficient storage space available. For additional information on virtual copies, see
“Virtual Copy Snapshots” (page 47).
NOTE: An HP 3PAR Virtual Copy license is required to create virtual copies. For more information,
see “HP 3PAR Software” (page 10).
Exporting Virtual Volumes
For a host to see a virtual volume, the volume must be exported as an LUN. Volumes are exported
by creating virtual volume-LUN (VLUN) pairings on the system. When you create VLUNs the system
produces both VLUN templates that establish export rules, and active VLUNs that the host sees as
a LUN or attached disk device. For more information about active VLUNs, VLUN templates, and
VLUN template types, see “Exporting Virtual Volumes” (page 50).
HP 3PAR Storage Concepts and Terminology 9