Advanced disk arrays provide methods to create copies of physical volumes (disks or LUNs) from the hardware side.
You can create a hardware snapshot (such as an EMC BCV™ or Hitachi ShadowImage™), a hardware mirror, or a hardware clone. You can also use dd or a similar command to clone the disk content.
If the physical volumes are VxVM disks, using a hardware copy method also copies the configuration data stored in the private region of the VxVM managed disk. The hardware disk copy becomes a duplicate of the original VxVM disk. For VxVM to handle the duplicated disk images correctly, VxVM must distinguish between the original and duplicate disk images.
VxVM detects that a disk is a hardware copy, to ensure that the duplicate disks are not confused with the original disks. This functionality enables the server to import a consistent set of disks. By default, VxVM imports the original physical volume but VxVM also enables you to work with the hardware copies on the same server. VxVM provides special options to import a disk group with the cloned images and make a cloned disk group with a unique identity. With care, you can manage multiple sets of hardware copies, even from the same server.
See Importing a disk group containing hardware cloned disks .
VxVM provides the following functionality to handle hardware copies: