AIX Version 4.3 Differences Guide

• The new option -B creates a big VG format volume group. This can
accommodate up to 128 physical volumes and 511 logical volumes (one
reserved for LVM internal use).
• If you do not use the -B option, the mkvg command will create the a VG with
1016*factor(-t) physical partitions and 32/factor(-t) disks per volume group.
• The option -G creates the volume group with enough space reserved at the
beginning of the disk to expand the VGDA to include 1024 disks in the future
without having to migrate the physical partitions.
Following is an example of the mkvg command. To create a big VG, testvg, on
hdisk1, enter:
# mkvg -B -y testvg hdisk1
To see the attributes of this VG, enter:
# lsvg testvg
VOLUME GROUP: testvg VGIDENTIFIER:061515169c44a3e
VG STATE: active PP SIZE: 4 megabyte(s)
VG PERMISSION: read/write TOTAL PPs: 80 (320megabytes)
MAX LVs: 512 FREE PPs: 80 (320 megabytes)
LVs: 0 USED PPs: 0 (0 megabytes)
OPEN LVs: 0 QUORUM: 2
TOTAL PVs: 1 VG DESCRIPTORS: 2
STALE PVs: 0 STALE PPs: 0
ACTIVE PVs: 1 AUTO ON: yes
MAX PPs per PV: 1016 MAX PVs: 128
This example shows the new limit values for big VG: MAX PVs is 128 and MAX
LVs is 512.
The chvg Command
The option -B converts a small VG to a big VG. Once all the logical volumes are
in closed/synced state (file systems unmounted), and if all the physical volumes
are in the ACTIVE state in the volume group, the -B flag can be used to convert
the small VG to a big VG format. This operation expands the VGDA/VGSA to
change the total number of disks that can be added to the volume group from 32
to 128.
If you want to convert the rootvg, you will get the following error message:
# chvg -B rootvg
0516-1212 chvg: rootvg cannot be converted to the big volume group format.
0516-732 chvg: Unable to change volume group rootvg.
If both -t and -B flags are specified, factor will be updated first, and then the VG
is converted to the big VG format (sequential operation).
First create a small VG, testvg, on hdisk1:
#mkvg -y testvg hdisk1
To see the small VG information, enter:
#lsvg hdisk1
VOLUME GROUP: testvg VG IDENTIFIER: 00615151692724b1
VG STATE: active PP SIZE: 4 megabyte(s)
VG PERMISSION: read/write TOTAL PPs: 81 (324 megabytes)
Logical Volume Manager Enhancements 89