AIX LVM - Determining VG Type (SVG/Small/Big)

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LVM has three different volume group types (SVG, Big, and Small). 

To determine the VG type, one can use the 'lsvg' command to compare the volume group properties with the default volume group properties in the following table.

Using the 'lsvg [vgname]' command, we see the defaults for a small VG from the preceding table in bold.

# lsvg vg00

VOLUME GROUP:       vg00                     VG IDENTIFIER:  00c10a0000004c0000000164d7fbda05
VG STATE:           active                   PP SIZE:        64 megabyte(s)
VG PERMISSION:      read/write               TOTAL PPs:      639 (40896 megabytes)
MAX LVs:            256                      FREE PPs:       639 (40896 megabytes)
LVs:                0                        USED PPs:       0 (0 megabytes)
OPEN LVs:           0                        QUORUM:         2 (Enabled)
TOTAL PVs:          1                        VG DESCRIPTORS: 2
STALE PVs:          0                        STALE PPs:      0
ACTIVE PVs:         1                        AUTO ON:        yes
MAX PPs per VG:     32512
MAX PPs per PV:     1016                     MAX PVs:        32
LTG size (Dynamic): 256 kilobyte(s)          AUTO SYNC:      no
HOT SPARE:          no                       BB POLICY:      relocatable
PV RESTRICTION:     none                     INFINITE RETRY: no
DISK BLOCK SIZE:    512                      CRITICAL VG:    no
FS SYNC OPTION:     no

If the defaults were not changed during VG creation and all three MAX values match the default chart, the VG is of that type.  However, an admin can change any of the three MAX values by customizing mkvg or using chvg.  Therefore, if any of the three MAX values do not match the default values in the chart, an admin either created the VG with custom settings or changed the VG using the 'chvg' command.

Now let's look at an example of when one of the default values change and we need to use more detailed analysis and inference to determine the VG type.  We increase the factor for the small VG vg00, which decreases the Max PVs.

# chvg -t 16 vg00
0516-1164 chvg: Volume group vg00 changed.  With given characteristics vg00
        can include up to 2 physical volumes with 16256 physical partitions each.
# lsvg vg00
VOLUME GROUP:       vg00                     VG IDENTIFIER:  00c10a0000004c0000000164d7fbda05
VG STATE:           active                   PP SIZE:        64 megabyte(s)
VG PERMISSION:      read/write               TOTAL PPs:      639 (40896 megabytes)
MAX LVs:            256                      FREE PPs:       639 (40896 megabytes)
LVs:                0                        USED PPs:       0 (0 megabytes)
OPEN LVs:           0                        QUORUM:         2 (Enabled)
TOTAL PVs:          1                        VG DESCRIPTORS: 2
STALE PVs:          0                        STALE PPs:      0
ACTIVE PVs:         1                        AUTO ON:        yes
MAX PPs per VG:     32512
MAX PPs per PV:     16256                    MAX PVs:        2
LTG size (Dynamic): 256 kilobyte(s)          AUTO SYNC:      no
HOT SPARE:          no                       BB POLICY:      relocatable
PV RESTRICTION:     none                     INFINITE RETRY: no
DISK BLOCK SIZE:    512                      CRITICAL VG:    no
FS SYNC OPTION:     no

Now we cannot use the MAX PVs field for determining VG type.  We can still infer that vg00 is a small VG by looking at the MAX LVs and MAX PPs.  Only a small VG can have the default MAX LVs of 256 and MAX PPs of 32512.

In most cases, the current maximum volumes value will match the default maximum physical volume value.  If the maximum physical values do not match, the volume group type can be determined by using other volume group properties, such as maximum logical volumes.