Veritas Volume Manager 4.1 Administrator's Guide (HP-UX 11i v3, February 2007)

Specifying a Disk Group to Commands
132 VERITAS Volume Manager Administrators Guide
target address or to a different controller, the name mydg02 continues to refer to it. Disks
can be replaced by first associating a different physical disk with the name of the disk to
be replaced and then recovering any volume data that was stored on the original disk
(from mirrors or backup copies).
Having disk groups that contain many disks and VxVM objects causes the private region
to fill. In the case of large disk groups that are expected to contain more than several
hundred disks and VxVM objects, disks should be set up with larger private areas. A
major portion of a private region provides space for a disk group configuration database
that contains records for each VxVM object in that disk group. Because each configuration
record takes up 256 bytes (or one quarter of a block), the number of records that can be
created in a disk group can be estimated from the configuration database copy size. The
copy size in blocks can be obtained from the output of the command vxdg list
diskgroup as the value of the permlen parameter on the line starting with the string
config:”. This value is the smallest of the len values for all copies of the configuration
database in the disk group. The amount of remaining free space in the configuration
database is shown as the value of the free parameter. An example is shown in
Displaying Disk Group Information” on page 135. One way to overcome the problem of
running out of free space is to split the affected disk group into two separate disk groups.
See “Reorganizing the Contents of Disk Groups” on page 155 for details.
For information on backing up and restoring disk group configurations, see “Backing Up
and Restoring Disk Group Configuration Data” on page 174.
Specifying a Disk Group to Commands
Note Most VxVM commands require superuser or equivalent privileges.
Many VxVM commands allow you to specify a disk group using the -g option. For
example, the following command creates a volume in the disk group, mktdg:
# vxassist -g mktdg make mktvol 5g
The block special device corresponding to this volume is:
/dev/vx/dsk/mktdg/mktvol