Ultimate LVM Cheat Sheet for Linux Sysadmins

Ultimate LVM Cheat Sheet for Linux Sysadmins

A complete reference for managing LVM on Linux systems. Covers creation, management, snapshots, thin provisioning, monitoring, troubleshooting, and best practices.

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🔹 LVM Concepts

• PV (Physical Volume) – Physical disk or partition used by LVM.
• VG (Volume Group) – Pool of storage made from PVs.
• LV (Logical Volume) – Virtual disk created from VG.
• PE / LE (Physical / Logical Extents) – Storage allocation unit.
• Snapshot – Point-in-time copy of an LV.
• Thin LV – Logical volume with on-demand storage allocation.
• Mirror / Stripe – LV layouts for redundancy and performance.

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🔹 Physical Volumes (PV)

• Create PV:

  sudo pvcreate /dev/sdb
  

• Display PV info:

  pvdisplay
  pvs
  

• Remove PV:

  sudo pvremove /dev/sdb
  

• Move PV data:

  pvmove /dev/sdb
  

• Backup PV metadata:

  pvcreate --restorefile /root/pvmetadata.bak /dev/sdb
  

• Recover PV metadata:

  vgcfgrestore vg_name
  

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🔹 Volume Groups (VG)

• Create VG:

  sudo vgcreate vg_data /dev/sdb /dev/sdc
  

• List VGs:

  vgdisplay
  vgs
  

• Extend VG (add PV):

  sudo vgextend vg_data /dev/sdd
  

• Reduce VG (remove PV):

  sudo vgreduce vg_data /dev/sdd
  

• Rename VG:

  sudo vgrename old_name new_name
  

• Remove VG:

  sudo vgremove vg_data
  

• Check VG free space:

  vgdisplay vg_data
  vgs
  

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🔹 Logical Volumes (LV)

• Create LV:

  sudo lvcreate -n lv_data -L 10G vg_data
  

• Create LV using 100% free space:

  sudo lvcreate -l 100%FREE -n lv_data vg_data
  

• Display LVs:

  lvdisplay
  lvs
  

• Remove LV:

  sudo lvremove /dev/vg_data/lv_data
  

• Resize LV (grow):

  sudo lvextend -L +5G /dev/vg_data/lv_data
  resize2fs /dev/vg_data/lv_data   # ext4
  xfs_growfs /mount/point          # XFS
  

• Resize LV (shrink – risky!):

  sudo lvreduce -L 5G /dev/vg_data/lv_data
  resize2fs /dev/vg_data/lv_data
  

• Rename LV:

  sudo lvrename vg_data lv_data lv_backup
  

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🔹 LV Snapshots

• Create snapshot:

  sudo lvcreate -s -n lv_data_snap -L 1G /dev/vg_data/lv_data
  

• List snapshots:

  lvs -a
  

• Remove snapshot:

  sudo lvremove /dev/vg_data/lv_data_snap
  

• Restore from snapshot:

  lvconvert --merge /dev/vg_data/lv_data_snap
  

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🔹 Thin Provisioning

• Create thin pool:

  lvcreate -L 50G -T vg_data/thinpool
  

• Create thin LV:

  lvcreate -V 10G -T vg_data/thinpool -n lv_thin
  

• List thin LVs:

  lvs -a -o+seg_monitor
  

• Resize thin LV:

  lvextend -L +5G /dev/vg_data/lv_thin
  

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🔹 Advanced Layouts

• Striped LV (performance):

  lvcreate -i2 -I64 -L 20G -n lv_striped vg_data /dev/sdb /dev/sdc
  

• Mirrored LV (redundancy):

  lvcreate -m1 -L 10G -n lv_mirror vg_data
  

• Convert to mirrored LV:

  lvconvert -m1 /dev/vg_data/lv_data
  

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🔹 Mounting & Filesystems

• Format LV:

  mkfs.ext4 /dev/vg_data/lv_data
  mkfs.xfs /dev/vg_data/lv_data
  

• Mount LV:

  sudo mount /dev/vg_data/lv_data /mnt/data
  

• Add to /etc/fstab:

  /dev/vg_data/lv_data  /mnt/data  ext4  defaults  0 2
  

• Check LV usage:

  df -h /mnt/data
  

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🔹 Monitoring & Troubleshooting

• Check free space in VG:

  vgdisplay vg_data
  vgs
  

• Check LV sizes:

  lvs
  lvdisplay
  

• Check PVs and extents:

  pvdisplay
  pvs
  

• Check filesystem on LV:

  fsck /dev/vg_data/lv_data
  

• Recover VG/LV metadata:

  vgcfgrestore vg_data
  lvconvert --repair /dev/vg_data/lv_data
  

• Activate / Deactivate LV:

  lvchange -ay /dev/vg_data/lv_data
  lvchange -an /dev/vg_data/lv_data
  

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🔹 Backup & Restore

• Backup LVM metadata:

  vgcfgbackup vg_data
  

• Restore LVM metadata:

  vgcfgrestore vg_data
  

• Use snapshots for backups:

  lvcreate -s -n lv_data_snap -L 1G /dev/vg_data/lv_data
  tar -czvf /backup/lv_data.tar.gz /mnt/data
  lvremove /dev/vg_data/lv_data_snap
  

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🔹 LVM Legend

• PV – Physical Volume
• VG – Volume Group
• LV – Logical Volume
• PE / LE – Physical / Logical extents
• Snapshot – Point-in-time copy of an LV
• Thin LV – On-demand allocated LV
• Mirror / Stripe – LV layout for redundancy/performance
• Thin Pool – Storage pool for thin LVs
• lvextend / lvreduce – Resize LVs
• vgextend / vgreduce – Resize VGs
• pvmove – Move data between PVs

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🔹 Best Practices

• Always backup data before resizing or removing LVs.
• Use snapshots before risky operations.
• Monitor VG free space regularly: vgs / vgdisplay.
• Keep LVs logically organized by purpose (/var, /home, /data).
• Avoid shrinking LVs unless filesystem contents are fully verified.
• Use RAID underneath LVM for redundancy and performance.
• Document LVM layout for disaster recovery.
• Use thin provisioning carefully, monitor usage to avoid overcommit.
• Periodically check filesystem integrity on LVs: fsck or xfs_repair.
• Use activation/deactivation of LVs to manage maintenance safely.