244Creating volumes

Creating a volume on specific disks

Creating a volume on specific disks

VxVM automatically selects the disks on which each volume resides, unless you specify otherwise. If you want a volume to be created on specific disks, you must designate those disks to VxVM. More than one disk can be specified.

To create a volume on a specific disk or disks, use the following command:

#vxassist [-b] [-g diskgroup] make volume length \ [layout=layout] diskname ...

For example, to create the volume volspec with length 5 gigabytes on disks mydg03 and mydg04, use the following command:

#vxassist -b -g mydg make volspec 5g mydg03 mydg04

The vxassist command allows you to specify storage attributes. These give you control over the devices, including disks, controllers and targets, which vxassist uses to configure a volume. For example, you can specifically exclude disk mydg05:

#vxassist -b -g mydg make volspec 5g !mydg05 or exclude all disks that are on controller c2:

#vxassist -b -g mydg make volspec 5g !ctlr:c2 or include only disks on controller c1 except for target t5:

#vxassist -b -g mydg make volspec 5g ctlr:c1 !target:c1t5

If you want a volume to be created using only disks from a specific disk group, use the -goption to vxassist, for example:

#vxassist -g bigone -b make volmega 20g bigone10 bigone11 or alternatively, use the diskgroup attribute:

#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.”