# Logical Volume Manager command usage (lvm)

###### tags: `linux` `lvm`

# term
PV - physical volume
VG - volume group
PE - physical extent
LV - logical volume

### list current lvm

root@develop:/home/ycheng# lvmdiskscan 
  /dev/vda2 [     <20.00 GiB] 
  /dev/vdb  [      20.00 GiB] 
  /dev/vdc  [      20.00 GiB] 
  2 disks
  1 partition
  0 LVM physical volume whole disks
  0 LVM physical volumes

### create / remove PV

root@develop:/home/ycheng# pvcreate /dev/vdb
  Physical volume "/dev/vdb" successfully created.
root@develop:/home/ycheng# pvcreate /dev/vdc
  Physical volume "/dev/vdc" successfully created.

root@develop:/home/ycheng# lvmdiskscan 
  /dev/vda2 [     <20.00 GiB] 
  /dev/vdb  [      20.00 GiB] LVM physical volume
  /dev/vdc  [      20.00 GiB] LVM physical volume
  0 disks
  1 partition
  2 LVM physical volume whole disks
  0 LVM physical volumes

root@develop:/home/ycheng# pvdisplay 
  "/dev/vdc" is a new physical volume of "20.00 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/vdc
  VG Name               
  PV Size               20.00 GiB
  Allocatable           NO
  PE Size               0   
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               LraVsw-U2HV-e2nA-z7rc-qKtx-QVmr-YNk0dF
   
  "/dev/vdb" is a new physical volume of "20.00 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/vdb
  VG Name               
  PV Size               20.00 GiB
  Allocatable           NO
  PE Size               0   
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               o4dT1U-SkDI-lunc-2Q7n-60OJ-40TL-72zoFB

!!! remove PV
pvremove < PV Name >

### create / remove VG

root@develop:/home/ycheng# vgcreate vg1 /dev/vdb /dev/vdc
  Volume group "vg1" successfully created

root@develop:/home/ycheng# vgdisplay 
  --- Volume group ---
  VG Name               vg1
  System ID             
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  1
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                0
  Open LV               0
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               39.99 GiB
  PE Size               4.00 MiB
  Total PE              10238
  Alloc PE / Size       0 / 0   
  Free  PE / Size       10238 / 39.99 GiB
  VG UUID               OwIsAL-iQSB-FJb0-dGUG-O4ro-1iNK-sw7Baf

!!! create VG with PE size to 128MiB
vgcreate -s 128 vg1 /dev/vdb /dev/vdc
!!! remove VG
vgremove vg1
!!! maximum 65534 PEs.

### create /remove LV

root@develop:/home/ycheng# lvcreate -L 8G -n lv1 vg1
  Logical volume "lv1" created.

root@develop:/home/ycheng# lvcreate -l 100%FREE -n lv2 vg1
  Logical volume "lv2" created.

root@develop:/home/ycheng# lvdisplay 
  --- Logical volume ---
  LV Path                /dev/vg1/lv1
  LV Name                lv1
  VG Name                vg1
  LV UUID                03jsBD-3XKC-88oZ-XHwJ-uJHw-J92j-MtTGdL
  LV Write Access        read/write
  LV Creation host, time develop, 2020-11-15 05:46:58 +0000
  LV Status              available
  # open                 0
  LV Size                8.00 GiB
  Current LE             2048
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:0
   
  --- Logical volume ---
  LV Path                /dev/vg1/lv2
  LV Name                lv2
  VG Name                vg1
  LV UUID                zMhcOs-Xpib-SSyA-fmeI-6puj-k3v8-NXAsb6
  LV Write Access        read/write
  LV Creation host, time develop, 2020-11-15 05:47:59 +0000
  LV Status              available
  # open                 0
  LV Size                31.99 GiB
  Current LE             8190
  Segments               2
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:1

!!! create "striped" allocation type LV 8GB
root@develop:/home/ycheng# lvcreate --type striped -i 2 -L 8G -n striped_lv1 vg1
  Using default stripesize 64.00 KiB.
  Logical volume "striped_lv1" created.

!!! allocate 100% free extends to create new LV. "-l < extends number >"
root@develop:/home/ycheng# lvcreate --type striped -i 2 -l 100%FREE -n striped_lv2 vg1
  Using default stripesize 64.00 KiB.
  Logical volume "striped_lv2" created.

!!! remove LV
lvremove /dev/vg1/striped_lv2

### create / remove snapshot and merge (recovery)

root@develop:/home/ycheng# lvcreate -s -L 8G -n snap_striped_lv1 vg1/striped_lv1
  Using default stripesize 64.00 KiB.
  Logical volume "snap_striped_lv1" created.

root@develop:/home/ycheng# lvconvert --merge vg1/snap_striped_lv1
  Merging of volume vg1/snap_striped_lv1 started.
  vg1/striped_lv1: Merged: 100.00%

!!! remove snapshot
lvremove 

### resize LV

root@develop:/home/ycheng# lvscan 
  ACTIVE            '/dev/vg1/striped_lv1' [8.00 GiB] inherit

root@develop:/home/ycheng# lvresize -L +4G vg1/striped_lv1
  Using stripesize of last segment 64.00 KiB
  Size of logical volume vg1/striped_lv1 changed from 8.00 GiB (2048 extents) to 12.00 GiB (3072 extents).
  Logical volume vg1/striped_lv1 successfully resized.

### remove PV from VG

pvmove /dev/vdc
vgreduce vg1 /dev/vdc
pvremove /dev/vdc

### rename VG

root@develop:/home/ycheng# vgscan 
  Reading volume groups from cache.
  Found volume group "vg1" using metadata type lvm2
root@develop:/home/ycheng# vgrename vg1 new_vg1
  Volume group "vg1" successfully renamed to "new_vg1"
root@develop:/home/ycheng# vgscan 
  Reading volume groups from cache.
  Found volume group "new_vg1" using metadata type lvm2

### other commands

vgextend - add new PV to VG
vgchange - change VG attributes
lvextend - increase LV size
lvreduce - reduce LV size