Veritas Volume Manager 5.0.1 Administrator's Guide, HP-UX 11i v3, First Edition, November 2009

How data is stored
There are several methods used to store data on physical disks. These methods
organize data on the disk so the data can be stored and retrieved efficiently. The
basic method of disk organization is called formatting. Formatting prepares the
hard disk so that files can be written to and retrieved from the disk by using a
prearranged storage pattern.
Hard disks are formatted, and information stored, using two methods:
physical-storage layout and logical-storage layout. VxVM uses the logical-storage
layout method.
See “How VxVM handles storage management” on page 23.
How VxVM handles storage management
VxVM uses the following types of objects to handle storage management:
Physical disks, LUNs (virtual disks implemented in hardware), or
other hardware with block and raw operating system device
interfaces that are used to store data.
See “Physical objects” on page 23.
Physical objects
When one or more physical disks are brought under the control
of VxVM, it creates virtual objects called volumes on those physical
disks. Each volume records and retrieves data from one or more
physical disks. Volumes are accessed by file systems, databases,
or other applications in the same way that physical disks are
accessed. Volumes are also composed of other virtual objects
(plexes and subdisks) that are used in changing the volume
configuration. Volumes and their virtual components are called
virtual objects or VxVM objects.
See “Virtual objects” on page 29.
Virtual objects
Physical objects
A physical disk is the basic storage device (media) where the data is ultimately
stored. You can access the data on a physical disk by using a device name to locate
the disk. The physical disk device name varies with the computer system you use.
Not all parameters are used on all systems.
Figure 1-1 shows how a physical disk and device name (devname) are illustrated
in this document.
23Understanding Veritas Volume Manager
How VxVM handles storage management