Linux LVM is complicated alchemy. It’s entirely possible this is very wrong.

Physical Volumes (PV) consist of a group of physical disks (disks, partitions, or LUNs). A Volume Group (VG) consists of some number of PVs. Logical Volumes are virtual disk partitions on top of the VG.

Note

Some of this was taken from howtogeek The instructions there give a lot more detail.

View current lvm info

root@buzzell:/var/VM# pvdisplay
  --- Physical volume ---
  PV Name               /dev/sda3
  VG Name               buzzell-vg
  PV Size               28.84 GiB / not usable 4.00 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              7382
  Free PE               0
  Allocated PE          7382
  PV UUID               qeoUD3-Yj11-Z7Jl-kSkR-uo4j-XTXz-OF3y4g

  --- Physical volume ---
  PV Name               /dev/sdb
  VG Name               buzzell-vg
  PV Size               149.01 GiB / not usable 3.89 MiB
  Allocatable           yes
  PE Size               4.00 MiB
  Total PE              38146
  Free PE               2306
  Allocated PE          35840
  PV UUID               3SCOg4-Wr50-Lped-6KvB-taJE-KhUd-innUoN

Create a partition

Apparently not always necessary or something.

# fdisk /dev/sdb

Create a physical volume

# pvcreate /dev/sdb1

Add to the volume group

# lvs
# vgextend buzzell-vg /dev/sdb1

Create a logical volume

# lvcreate -L 50G -n var buzzell-vg

Format and Mount

# mkfs -t ext4 /dev/mapper/buzzell--vg-var
# mount /dev/mapper/buzzell--vg-var /mnt

Display information about a volume group

root@buzzell:/var/VM# vgdisplay
  --- Volume group ---
  VG Name               buzzell-vg
  System ID
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  9
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                3
  Open LV               3
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               177.84 GiB
  PE Size               4.00 MiB
  Total PE              45528
  Alloc PE / Size       20182 / 78.84 GiB
  Free  PE / Size       25346 / 99.01 GiB
  VG UUID               bPlGsE-Vmza-glR9-1fDd-SXtX-rR0A-F72a24

Alternatives

pvs, vgs, lvs

Display logical volumes

root@buzzell:/var/VM# lvdisplay
  --- Logical volume ---
  LV Path                /dev/buzzell-vg/root
  LV Name                root
  VG Name                buzzell-vg
  LV UUID                QLwq48-72bW-TzQ9-g10P-rim2-cmwo-7CcoVk
  LV Write Access        read/write
  LV Creation host, time buzzell, 2016-09-05 19:22:25 -0400
  LV Status              available
  # open                 1
  LV Size                20.93 GiB
  Current LE             5359
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           252:0

  --- Logical volume ---
  LV Path                /dev/buzzell-vg/swap_1
  LV Name                swap_1
  VG Name                buzzell-vg
  LV UUID                ui1amd-cA0f-bPrC-pGiJ-IUG4-Qc4L-qRlQGQ
  LV Write Access        read/write
  LV Creation host, time buzzell, 2016-09-05 19:22:25 -0400
  LV Status              available
  # open                 2
  LV Size                7.90 GiB
  Current LE             2023
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           252:1

  --- Logical volume ---
  LV Path                /dev/buzzell-vg/var
  LV Name                var
  VG Name                buzzell-vg
  LV UUID                ou9CP7-9Gkg-kbqb-OiAS-S7N5-90ki-3RQcsv
  LV Write Access        read/write
  LV Creation host, time buzzell, 2016-09-22 10:52:46 -0400
  LV Status              available
  # open                 1
  LV Size                50.00 GiB
  Current LE             12800
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           252:2

More specific logical volume info

root@buzzell:/var/VM# lvdisplay -m /dev/buzzell-vg/var
  --- Logical volume ---
  LV Path                /dev/buzzell-vg/var
  LV Name                var
  VG Name                buzzell-vg
  LV UUID                ou9CP7-9Gkg-kbqb-OiAS-S7N5-90ki-3RQcsv
  LV Write Access        read/write
  LV Creation host, time buzzell, 2016-09-22 10:52:46 -0400
  LV Status              available
  # open                 1
  LV Size                50.00 GiB
  Current LE             12800
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           252:2

  --- Segments ---
  Logical extents 0 to 12799:
    Type                linear
    Physical volume     /dev/sdb
    Physical extents    0 to 12799