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

236 Creating volumes
Creating a volume on specific disks
# vxassist -b make volmega 20g diskgroup=bigone bigone10 \
bigone11
Note: Any storage attributes that you specify for use must belong to the disk group.
Otherwise, vxassist will not use them to create a volume.
You can also use storage attributes to control how
vxassist uses available storage, for
example, when calculating the maximum size of a volume, when growing a volume or
when removing mirrors or logs from a volume. The following example excludes disks
dgrp07 and dgrp08 when calculating the maximum size of RAID-5 volume that
vxassist can create using the disks in the disk group dg:
# vxassist -b -g dgrp maxsize layout=raid5 nlog=2 !dgrp07 \
!dgrp08
See the vxassist(1M) manual page for more information about using storage attributes.
It is also possible to control how volumes are laid out on the specified storage as described
in the next section “Specifying ordered allocation of storage to volumes.”
Specifying ordered allocation of storage to volumes
Ordered allocation gives you complete control of space allocation. It requires that the
number of disks that you specify to the
vxassist command must match the number of
disks that are required to create a volume. The order in which you specify the disks to
vxassist is also significant.
If you specify the
-o ordered option to vxassist when creating a volume, any storage
that you also specify is allocated in the following order:
1 Concatenate disks.
2 Form columns.
3 Form mirrors.
For example, the following command creates a mirrored-stripe volume with 3 columns
and 2 mirrors on 6 disks in the disk group, mydg:
# vxassist -b -g mydg -o ordered make mirstrvol 10g \
layout=mirror-stripe ncol=3 \
mydg01 mydg02 mydg03 mydg04 mydg05 mydg06
This command places columns 1, 2 and 3 of the first mirror on disks mydg01, mydg02
and mydg03 respectively, and columns 1, 2 and 3 of the second mirror on disks mydg04,
mydg05 and mydg06 respectively. This arrangement is illustrated in Figure 7-1.