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

162 Creating and administering disk groups
Creating a disk group
mydg mydg02 c0t11d0 c0t11d0 0 4443310 -
newdg newdg01 c0t12d0 c0t12d0 0 4443310 -
newdg newdg02 c0t13d0 c0t13d0 0 4443310 -
oradg oradg01 c0t14d0 c0t14d0 0 4443310 -
To display free space for a disk group, use the following command:
# vxdg -g diskgroup free
where -g diskgroup optionally specifies a disk group.
For example, to display the free space in the disk group, mydg, use the following
command:
# vxdg -g mydg free
The following example output shows the amount of free space in sectors:
DISK DEVICE TAG OFFSET LENGTH FLAGS
mydg01 c0t10d0 c0t10d0 0 4444228 -
mydg02 c0t11d0 c0t11d0 0 4443310 -
Creating a disk group
Data related to a particular set of applications or a particular group of users may need to be
made accessible on another system. Examples of this are:
■ A system has failed and its data needs to be moved to other systems.
■ The work load must be balanced across a number of systems.
Disks must be placed in one or more disk groups before VxVM can use the disks for
volumes. It is important that you locate data related to particular applications or users on
an identifiable set of disks. When you need to move these disks, this allows you to move
only the application or user data that should be moved.
A disk group must have at least one disk associated with it. A new disk group can be
created when you use menu item 1 (Add or initialize one or more
disks) of the vxdiskadm command to add disks to VxVM control, as described in
“Adding a disk to VxVM” on page 97. The disks to be added to a disk group must not
belong to an existing disk group.
You can also use the vxdiskadd command to create a new disk group:
# vxdiskadd c1t0d0
where c1t0d0 in this example is the device name of a disk that is not currently assigned
to a disk group. The command dialog is similar to that described for the vxdiskadm
command in “Adding a disk to VxVM” on page 97.
Disk groups can also be created by using the vxdg init command:
# vxdg init diskgroup [cds=on|off] diskname=devicename
For example, to create a disk group named mktdg on device c1t0d0:
# vxdg init mktdg mktdg01=c1t0d0
The disk specified by the device name, c1t0d0, must have been previously initialized
with vxdiskadd or vxdiskadm, and must not currently belong to a disk group.