Modify the VG type in AIX and how to change the VG

VG type in AIX

There are three types of VG in AIX:

VG type	Maximum PVs	Maximum LVs	Maximum PPs per VG	Maximum PP size
Normal VG	32	256	32,512 (1016*32)	1 GB
Big VG	128	512	130,048 (1016*128)	1 GB
Scalable VG	1024	4096	2,097,152	128 GB

First, how can I check what type of VG is?

Use the following method:

For example, hdisk2 belongs to datavg.

Run # readvgda hdisk2 | grep type

... Readvgda_type: smallvg

Vgtype: 0

Datavg is normal VG.

What is most used during maintenance is how to balance the number of PP, PV, and LV in a VG.

How can I change the maximum number of PP in VG without changing the VG type?

You can modify the factor to balance the quantity of PP and PV.

For example:

# Lsvg datavg

Volume group: datavg vg identifier: 00f743384254c000000013808c3ac8d

Vg state: active pp size: 4 megabyte (s)

Vg permission: read/write TOTAL PPs: 48 (192 megabytes)

MAX LVs: 256 FREE PPs: 10 (40 megabytes)

LVs: 3 USED PPs: 38 (152 megabytes)

OPEN LVs: 2 QUORUM: 1 (Disabled)

TOTAL PVs: 2 vg descriptors: 3

STALE PVs: 0 STALE PPs: 0

ACTIVE PVs: 2 auto on: no

Concurrent: Enhanced-Capable Auto-Concurrent: Disabled

VG Mode: Non-Concurrent

MAX packets per VG: 32512

MAX PPs per PV: 1016 MAX PVs: 32

LTG size (Dynamic): 128 kilobyte (s) auto sync: no

Hot spare: no bb policy: relocatable

Pv restriction: none infinite retry: no

# Lsvg-p datavg

Datavg:

PV_NAME pv state total PPs FREE DISTRIBUTION

Hdisk2 active 24 5 04... 00... 00... 00... 01

Hdisk5 active 24 5 04... 00... 00... 00... 01

# Readvgda hdisk2 | grep type

... Readvgda_type: smallvg

Vgtype: 0

# Set-o vi

# Readvgda hdisk2 | grep factor

Factor: 1

# Chvg-t 2 datavg change factor to 2

0516-1164 chvg: Volume group datavg changed. With given characteristics datavg

Can include up to 16 physical volumes with 2032 physical partitions each.

# Lsvg datavg

Volume group: datavg vg identifier: 00f743384254c000000013808c3ac8d

Vg state: active pp size: 4 megabyte (s)

Vg permission: read/write TOTAL PPs: 48 (192 megabytes)

MAX LVs: 256 FREE PPs: 10 (40 megabytes)

LVs: 3 USED PPs: 38 (152 megabytes)

OPEN LVs: 2 QUORUM: 1 (Disabled)

TOTAL PVs: 2 vg descriptors: 3

STALE PVs: 0 STALE PPs: 0

ACTIVE PVs: 2 auto on: no

Concurrent: Enhanced-Capable Auto-Concurrent: Disabled

VG Mode: Non-Concurrent

MAX packets per VG: 32512

MAX PPs per PV: 2032 MAX PVs: 16

LTG size (Dynamic): 128 kilobyte (s) auto sync: no

Hot spare: no bb policy: relocatable

Pv restriction: none infinite retry: no

#

# Readvgda hdisk2 | grep factor

Factor: 2

Another way is to change the VG type to increase the maximum number of PP, PV, and LV.

# Chvg-B mndhb_vg_01 change VG to Big VG type

0516-1164 chvg: Volume group mndhb_vg_01 changed. With given characteristics mndhb_vg_01

Can include up to 64 physical volumes with 2032 physical partitions each.

# Lsvg mndhb_vg_01

Volume group: mndhb_vg_01 vg identifier: 00f743384154c000000013808c3ac8d

Vg state: active pp size: 4 megabyte (s)

Vg permission: read/write TOTAL PPs: 44 (176 megabytes)

MAX LVs: 512 FREE PPs: 6 (24 megabytes)

LVs: 3 USED PPs: 38 (152 megabytes)

OPEN LVs: 2 QUORUM: 1 (Disabled)

TOTAL PVs: 2 vg descriptors: 3

STALE PVs: 0 STALE PPs: 0

ACTIVE PVs: 2 auto on: no

Concurrent: Enhanced-Capable Auto-Concurrent: Disabled

VG Mode: Non-Concurrent

MAX packets per VG: 130048

MAX PPs per PV: 2032 MAX PVs: 64

LTG size (Dynamic): 128 kilobyte (s) auto sync: no

Hot spare: no bb policy: relocatable

Pv restriction: none infinite retry: no

# Readvgda hdisk2 | grep type

... Readvgda_type: bigvg

Vgtype: 1

Note that if you change the VG type to Scalable VG, you must first varyoffvg

# Varyoffvg datavg

# Chvg-G datavg

# Varyonvg datavg

We recommend that you select Scalable VG when creating a VG when deploying a new system. This eliminates 512 byte logical volume control block (LVCB) offset to affect aligned writes (often found on systems using raw LVs with Oracle databases) Restrictions

Note: During chvg-B and chvg-G operations, each pv in vg must have sufficient free space to store vgda changes.