Logical Volume Manager (Linux)

LVM available in Linux allows manage multiple physical volumes or entire hard disks. It supports among other functionalities:

• Create single logical volumes of multiple physical volumes or entire hard disks
• Add or remove volumes/disk dynamically
• Increase or decrease size of Logical Volumes (LVs)
• Create snapshots

LVM introduces the concept of Volume Groups (VGs) and Logical Volumes (LVs).

Configuration file: /etc/lvm/lvm.conf

Components

• lvmetad LVM metadata cache daemon

Basic commands

• List Volume Groups:vgs
  • vgscan, vgextend, vgdisplay
• List logical volumes: lvs, /lvdisplay/
• Resize LV:
  • lvresize
  • lvextend
  • lvreduce

• Display commands:

pvdisplay

lvdisplay

vgdisplay

• Create commands:

pvcreate

lvcreate

vgcreate

vgreduce

• Ls commands: pvs, lvs, vgs
• Scan commands: pvscan, vgscan
• PV commands: pvdisplay, pvresize, pvscan, pvcreate or pvcreate -vv
• LV commands: lvcreate, lvconvert
• VG commands: vgdisplay, vgcreate, vgcfgbackup, vgscan
• LVM commands: lvm dumpconfig

Advanced commands

• lvchange — Change attributes of the Logical Volume Manager.
• lvmdiskscan. Deprecated: used lvs. Scan for all devices visible to LVM2.
• lvmdump — Create lvm2 information dumps for diagnostic purposes.

Activities

Basic

1. Read StackOverflow LVMs questions: https://superuser.com/questions/tagged/lvm?tab=Votes
2. Read Configuring and Managing Logical Volumens in RHEL 8: https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html-single/configuring_and_managing_logical_volumes/index
3. Configure an LVM Volume with an ext File Sytem: https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/high_availability_add-on_administration/s1-lvmsetupnfs-haaa

Advanced

Before doing these exercises make your you have a backup of your data.

1. Convert a Linear Device to a RAID device: https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html-single/configuring_and_managing_logical_volumes/index#proc_converting-linear-to-raid-configure-manage-raid
2. Read LVM Changelog: sourceware.org/git/?p=lvm2.git;a=blame;f=WHATS_NEW;hb=9cad26be321844868a904c7b07bebe37be4e0169

See also

• LVM: LVM errors LVM scan commands lkvmetad, Add a new disk

scan: pvscan vgscan

LVM: lvs lvmscan lvm fullreport lvmreport lvmconfig lvmdump lvmcheck lvm dumpconfig

Scan: pvs vgs lvs pvscan vgscan

PV: pvcreate pvremove pvscan pvremove pvscan pvs pvchange pvck pvdisplay pvresize

LV: lvdisplay lvcreate lvremove, lvresize, lvextend, lvreduce, lvrename

VG: vgdisplay,vgcreate,vgremove, vgextend, vgreduce, vgscan, vgchange, vgrename, vgcfgbackup, vgcfgrestore, vgimportclone, vgck

Check commands: pvck vgck

• mdadm and ZFS
• resize2fs file system resizer for ext2/ext3/ext4 (resize2fs /dev/mapper/VolGroup-lv_root) (for ext4 only).. Code: https://github.com/tytso/e2fsprogs/blob/master/resize/resize2fs.c
• Ansible LV module: https://docs.ansible.com/ansible/latest/modules/lvol_module.html#lvol-module
• dmsetup
• UUID

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Original Source: https://en.wikiversity.org/wiki/Linux_Administration/Devices_and_Filesystems/LVM