VERITAS Volume Manager 3.1 Administrator's Guide

Introduction to Volume Manager
Volumes and Virtual Objects
Chapter 132
default name that typically takes the form disk ## . See Figure 1-1,
Example of a VM Disk, which shows a VM disk with a media name of
disk01 that is assigned to the disk devname.
Figure 1-1 Example of a VM Disk
Disk Groups
A disk group is a collection of VM disks that share a common
configuration. A disk group configuration is a set of records with detailed
information about related Volume Manager objects, their attributes, and
their connections. The default disk group is rootdg (the root disk group).
You can create additional disk groups as necessary. Disk groups allow
the administrator to group disksinto logicalcollections. A disk group and
its components can be moved as a unit from one host machine to another.
Volumes are created within a disk group. A given volume must be
configured from disks in the same disk group.
Subdisks
A subdisk is a set of contiguous disk blocks. A block is a unit of space on
the disk. Volume Manager allocates disk space using subdisks. A VM
disk can be divided into one or more subdisks. Each subdisk represents a
specific portion of a VM disk, which is mapped to a specific region of a
physical disk.
The default name for a VM disk is disk ## (such as disk01) and the
default name for a subdisk is disk ##-## . As shown in Figure 1-2,
Example of a Subdisk,, disk01-01 is the name of the first subdisk on the
VM disk named disk01.
Physical DiskVM Disk
devname
disk01