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

http://www.hp.com/storage/spock
Virtual copies can be created and managed in groups to reduce the number of management tasks.
You can create a consistent group of virtual copies from a list of virtual volumes, and group virtual
copies into autonomic groups that are managed as a single virtual copy.
NOTE: Virtual copies are consistent at the virtual volume level, but not at the host file system or
application level. In other words, virtual copies only preserve the data that was written on the
source virtual volume before the virtual copy is created. Virtual copies do not preserve the data
that is resident within the application or file system buffers and is not flushed to disk before the
virtual copy is created.
HP offers optional HP 3PAR Recovery Manager DBA software to enable application-level consistent
snapshots. Contact HP Customer Support for more information.
Virtual Copy Snapshot Relationships
Base volumes are always read/write, but virtual copies can be read/write or read-only. The rules
that govern the relationships between a base volume and its virtual copies are based on the
difference between read/write and read-only volumes. Read-only copies must alternate. You can
make a read-only copy of a read/write volume, and you can only make a read/write copy of a
read-only volume. See Figure 9 (page 48) for an example of alternating read-only and read/write
virtual copy relationships.
Figure 9 Alternating Read-only and Read/Write Virtual Copies
See Figure 10 (page 48) for a more complex example of the possible relationships between a
parent base volume and its virtual copies.
Figure 10 Base Volume and Virtual Copy Relationships
48 Virtual Volumes