LVM cheat sheet

The chapter on one page: what to remember, the commands to have at your fingertips, and flashcards for quick revision.

The chapter in eight sentences

LVM stacks flexible layers on top of disks: physical volumes (PV) make up a volume group (VG), from which logical volumes (LV) are cut and given file systems or swap.
Build with pvcreate, vgcreate, lvcreate -n NAME -L SIZE VG (or -l 50%FREE), then mkfs and mount; the device is /dev/VG/LV.
Inspect with pvs, vgs, lvs (and -o +devices) and lsblk -f; the a in the LV Attr means active, o open.
Grow with lvextend -r -L +SIZE LV (or -l +100%FREE), while mounted; the -r also runs xfs_growfs or resize2fs.
A full group needs a new PV: pvcreate, then vgextend VG PV.
ext4 can be shrunk offline with lvreduce -r -L SIZE LV; XFS cannot be shrunk at all. Back up first.
Replace a disk online: vgextend (new), pvmove OLD NEW, vgreduce VG OLD, pvremove OLD.
Make volumes permanent with /dev/VG/LV (or UUID) in /etc/fstab; an inactive volume is fixed with lvchange -ay, and the layout is saved by vgcfgbackup.

Command	Does
`pvcreate DEV` · `pvs` · `pvdisplay`	Physical volumes
`vgcreate [-s 8M] VG DEV…` · `vgs` · `vgdisplay`	Volume groups
`lvcreate -n LV -L 1G VG` · `lvs` · `lvdisplay`	Logical volumes
`lvs -o +devices,lv_path`	Where each LV lives
`mkfs.xfs /dev/VG/LV` · `mount`	File system and mount

Command	Does
`lvrename VG old new` · `lvremove VG/LV`	Rename, remove
`vgremove VG` · `pvremove PV`	Remove group, PV
`lvchange -ay VG/LV` · `vgchange -ay VG`	Activate
`lvmdevices` · `pvs -a` · `pvscan`	Which devices LVM sees
`vgcfgbackup VG` · `/etc/lvm/backup`	Layout backup
fstab	`/dev/VG/LV /dir xfs defaults 0 0` · swap: `/dev/VG/LV none swap defaults 0 0`

LVM layers?: Disk/partition → PV → VG → LV → file system (or swap).
Show them?: pvs · vgs · lvs · lsblk -f · pvdisplay · vgdisplay · lvdisplay
Build in five commands?: pvcreate · vgcreate · lvcreate -n NAME -L SIZE VG · mkfs.xfs /dev/VG/LV · mount
Size options of lvcreate/lvextend?: -L 1G (size, +1G adds) · -l 50%FREE or +100%FREE (extents/percent)
Grow an LV and its file system?: lvextend -r -L +512M /dev/VG/LV (xfs_growfs / resize2fs inside)
Add a disk to a group?: pvcreate /dev/sdc1 · vgextend VG /dev/sdc1
Shrink?: ext4 only: lvreduce -r -L SIZE LV (unmounted). XFS cannot shrink.
Replace a disk online?: vgextend (new) · pvmove OLD NEW · vgreduce VG OLD · pvremove OLD
Rename, remove?: lvrename VG old new · lvremove VG/LV · vgremove VG · pvremove PV
fstab for an LV?: /dev/VG/LV /mnt xfs defaults 0 0 (update after lvrename)
LV does not exist for mount?: lvchange -ay VG/LV (check the a flag in lvs)
Layout backups?: vgcfgbackup · /etc/lvm/backup · vgcfgrestore; data needs its own backup