Veritas Volume Manager 5.0 Administrator's Guide (September 2006)

Chapter

Creating and administering

disk groups

This chapter describes how to create and manage disk groups. Disk groups are named

collections of disks that share a common configuration. Volumes are created within a disk

group and are restricted to using disks within that disk group.

Note: In releases of Veritas Volume Manager (VxVM) prior to 4.0, a system installed with

VxVM was configured with a default disk group, rootdg, that had to contain at least one

disk. By default, operations were directed to the rootdg disk group. From release 4.0

onward, VxVM can function without any disk group having been configured. Only when

the first disk is placed under VxVM control must a disk group be configured. There is no

longer a requirement that you name any disk group rootdg, and any disk group that is

named rootdg has no special properties because of this name. See “Specifying a disk

group to commands” on page 158 for more information about using disk group names that

are reserved for special purposes.

Additionally, prior to VxVM 4.0, some commands such as

vxdisk were able to deduce

the disk group if the name of an object was uniquely defined in one disk group among all

the imported disk groups. Resolution of a disk group in this way is no longer supported for

any command.

For a discussion of disk groups that are compatible with the Cross-platform Data Sharing

(CDS) feature of Veritas Volume Manager, see the Veritas Storage Foundation Cross-

Platform Data Sharing Administrator’s Guide. The CDS feature allows you to move

VxVM disks and objects between machines that are running under different operating

systems.

As system administrator, you can create additional disk groups to arrange your system’s

disks for different purposes. Many systems do not use more than one disk group, unless

they have a large number of disks. Disks can be initialized, reserved, and added to disk