LVM Common Tasks

Linux LVM

• Initializing disks or disk partitions
  For entire disks:

  $ pvcreate /dev/sda
  

  For partitions:

  $ pvcreate /dev/sda1
  

• Creating a volume group

  $ vgcreate <groupname> /dev/hda1 /dev/dhb1
  

• Activating a volume group

  $ vgchange -an
  $ vgchange -a y <groupname>
  

• Removing a volume group
  Deactivate the volume group:

  $ vgchange -a n <groupname>
  

  Remove the volume group

  $ vgremove <groupname>
  

• Adding physical volumes to a volume group

  $ vgextend <groupname> /dev/hdc1
                                ^^^^^^^^ new physical volume
  

• Removing physical volumes from a volume group
  Make sure that the physical volume isn’t used by any logical volumes

$ pvdisplay /dev/hda1

--- Physical volume ---
PV Name               /dev/hda1
VG Name               myvg
PV Size               1.95 GB / NOT usable 4 MB [LVM: 122 KB]
PV#                   1
PV Status             available
Allocatable           yes (but full)
Cur LV                1
PE Size (KByte)       4096
Total PE              499
Free PE               0
Allocated PE          499
PV UUID               Sd44tK-9IRw-SrMC-MOkn-76iP-iftz-OVSen7

Remove the physical volume

$ vgreduce <groupname> /dev/hda1

• Creating a logical volume
  To create a 1500MB linear LV named ‘testlv’ and its block device special ‘/dev/testvg/testlv’:

  $ lvcreate -L1500 -ntestlv testvg
  

  To create a 100 LE large logical volume with 2 stripes and stripe size 4 KB.

  $ lvcreate -i2 -I4 -l100 -nanothertestlv testvg
  

  To create an LV that uses the entire VG

  $ vgdisplay testvg | grep "Total PE"
  Total PE              10230 <--- using this value
  $ lvcreate -l 10230 testvg -n mylv
  

  To create an LV that use all the free VG

  $ vgdisplay -v testvg | grep "Free PE"
  Total PE / Free PE             10230 / 190230 <--- using this value
  $ lvcreate -l 10230 testvg -n mylv
  

  To allocate the logical volumene from a specific physical volume in the volume group.

  $ lvcreate -L 1500 -ntestlv testvg /dev/sdg
  

  Before mount lv, run mkfs to create file system

  mkfs xfs /dev/mapper/testvg-mylv
  

• Removing a logical volume

  $ umount /dev/myvg/homevol
  $ lvremove /dev/myvg/homevol
  lvremove -- do you really want to remove "/dev/myvg/homevol"? [y/n]: y
  lvremove -- doing automatic backup of volume group "myvg"
  lvremove -- logical volume "/dev/myvg/homevol" successfully removed
  

• Extending a logical volume

$ lvextend -L12G /dev/myvg/homevol
lvextend -- extending logical volume "/dev/myvg/homevol" to 12 GB
lvextend -- doing automatic backup of volume group "myvg"
lvextend -- logical volume "/dev/myvg/homevol" successfully extended

$ lvextend -L+1G /dev/myvg/homevol
lvextend -- extending logical volume "/dev/myvg/homevol" to 13 GB
lvextend -- doing automatic backup of volume group "myvg"
lvextend -- logical volume "/dev/myvg/homevol" successfully extended

Resizing file system
ext2/ext3

$ umount /dev/myvg/homevol/dev/myvg/homevol
$ resize2fs /dev/myvg/homevol
$ mount /dev/myvg/homevol /home

or

$ umount /dev/myvg/homevol/dev/myvg/homevol
$ ext2resize /dev/myvg/homevol
$ mount /dev/myvg/homevol /homek

reiserfs

$ resize_reiserfs -f /dev/myvg/homevol

or

$ umount /dev/myvg/homevol
$ resize_reiserfs /dev/myvg/homevol
$ mount -treiserfs /dev/myvg/homevol /home

xfs

$ xfs_growfs /home

jfs

$ mount -o remount,resize /home

• Reducing a logical volume
  There is no way to shrink XFS and JFS file system.
  ext2

$ umount /home
$ e2fsadm -L-1G /dev/myvg/homevol
$ mount /home

or

$ umount /home
$ resize2fs /dev/myvg/homevol 524288
$ lvreduce -L-1G /dev/myvg/homevol
$ mount /home

reiserfs

$ umount /home
$ resize_reiserfs -s-1G /dev/myvg/homevol
$ lvreduce -L-1G /dev/myvg/homevol
$ mount -treiserfs /dev/myvg/homevol /home

Reference:
http://tldp.org/HOWTO/LVM-HOWTO/initdisks.html

Written on November 15, 2017