System Administration

Linux Logical Volume Manager (LVM) Cheatsheet

Comprehensive LVM reference covering physical volume management, volume group operations, logical volume commands, snapshots, resizing, and common storage management workflows for Linux system administrators. Perfect for managing storage on VPS servers and cloud environments.

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LVM

LVM Architecture Hierarchy

1
Physical Volumes (PV)
Raw disk partitions or entire disks (/dev/sda1, /dev/sdb)
2
Volume Groups (VG)
Pool of storage combining multiple PVs (vg_data, vg_system)
3
Logical Volumes (LV)
Virtual partitions from VG space, mountable as filesystems (/dev/vg_data/lv_home)

Table of Contents

1. LVM Overview 2. Physical Volume Commands 3. Volume Group Commands 4. Logical Volume Commands 5. Filesystem Operations 6. LVM Snapshots 7. Common Workflows 8. Troubleshooting

LVM Overview

Logical Volume Manager (LVM) provides flexible disk management by abstracting physical storage into logical volumes that can be easily resized, moved, and managed.

Benefits

  • • Resize volumes on-the-fly
  • • Span multiple disks
  • • Create snapshots
  • • Easy migration

Use Cases

Key Components

  • • Physical Volumes (PV)
  • • Volume Groups (VG)
  • • Logical Volumes (LV)
  • • Physical Extents (PE)

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Physical Volume Commands

pvcreate - Create Physical Volume

Initialize a disk or partition for use with LVM.

# Create PV on a partition
sudo pvcreate /dev/sdb1

# Create PV on entire disk
sudo pvcreate /dev/sdc

# Create multiple PVs at once
sudo pvcreate /dev/sdb1 /dev/sdc1 /dev/sdd1

pvdisplay - Display Physical Volume Details

Show detailed information about physical volumes.

# Display all PVs with details
sudo pvdisplay

# Display specific PV
sudo pvdisplay /dev/sdb1

# Display in columns format
sudo pvdisplay -C

pvs - Physical Volume Summary

Quick summary of all physical volumes.

# List all PVs (concise)
sudo pvs

# Show with additional fields
sudo pvs -o +pv_used,pv_free

# Show all available fields
sudo pvs -o +all

pvscan - Scan for Physical Volumes

Scan all disks for physical volumes.

# Scan for all PVs
sudo pvscan

# Scan and cache results
sudo pvscan --cache

pvremove - Remove Physical Volume

Remove LVM labels from a physical volume.

# Remove PV (must not be in use)
sudo pvremove /dev/sdb1

# Force removal
sudo pvremove -ff /dev/sdb1

⚠️ Warning: Ensure the PV is not part of any VG before removing.

Volume Group Commands

vgcreate - Create Volume Group

Create a new volume group from one or more physical volumes.

# Create VG from single PV
sudo vgcreate vg_data /dev/sdb1

# Create VG from multiple PVs
sudo vgcreate vg_data /dev/sdb1 /dev/sdc1

# Create VG with specific PE size (default 4MB)
sudo vgcreate -s 8M vg_data /dev/sdb1

vgdisplay - Display Volume Group Details

Show detailed information about volume groups.

# Display all VGs
sudo vgdisplay

# Display specific VG
sudo vgdisplay vg_data

# Short format
sudo vgdisplay -s

vgs - Volume Group Summary

Quick summary of all volume groups.

# List all VGs
sudo vgs

# Show additional information
sudo vgs -o +vg_free,vg_size

# Show all fields
sudo vgs -o +all

vgextend - Extend Volume Group

Add physical volumes to an existing volume group.

# Add single PV to VG
sudo vgextend vg_data /dev/sdd1

# Add multiple PVs
sudo vgextend vg_data /dev/sdd1 /dev/sde1

vgreduce - Reduce Volume Group

Remove physical volumes from a volume group.

# Remove specific PV from VG
sudo vgreduce vg_data /dev/sdd1

# Remove all empty PVs
sudo vgreduce --all vg_data

💡 Note: Move data off the PV using pvmove before reducing.

vgremove - Remove Volume Group

Delete a volume group.

# Remove VG (must have no LVs)
sudo vgremove vg_data

# Force removal
sudo vgremove -f vg_data

vgscan - Scan for Volume Groups

Scan all disks for volume groups and rebuild cache.

# Scan for VGs
sudo vgscan

# Scan and rebuild cache
sudo vgscan --mknodes

Logical Volume Commands

lvcreate - Create Logical Volume

Create a new logical volume in a volume group.

# Create LV with specific size
sudo lvcreate -L 10G -n lv_home vg_data

# Create LV using percentage of VG
sudo lvcreate -l 100%FREE -n lv_data vg_data

# Create LV with percentage of VG
sudo lvcreate -l 50%VG -n lv_apps vg_data

# Create LV with number of extents
sudo lvcreate -l 2560 -n lv_web vg_data

lvdisplay - Display Logical Volume Details

Show detailed information about logical volumes.

# Display all LVs
sudo lvdisplay

# Display specific LV
sudo lvdisplay /dev/vg_data/lv_home

# Display by VG
sudo lvdisplay vg_data

lvs - Logical Volume Summary

Quick summary of all logical volumes.

# List all LVs
sudo lvs

# Show with additional fields
sudo lvs -o +lv_size,lv_path

# Show all fields
sudo lvs -o +all

lvextend - Extend Logical Volume

Increase the size of a logical volume.

# Extend by specific size
sudo lvextend -L +5G /dev/vg_data/lv_home

# Extend to specific total size
sudo lvextend -L 20G /dev/vg_data/lv_home

# Extend using all free space
sudo lvextend -l +100%FREE /dev/vg_data/lv_home

# Extend and resize filesystem automatically
sudo lvextend -L +5G -r /dev/vg_data/lv_home

💡 Tip: Use -r flag to automatically resize the filesystem after extending.

lvreduce - Reduce Logical Volume

Decrease the size of a logical volume.

# Reduce by specific size
sudo lvreduce -L -2G /dev/vg_data/lv_home

# Reduce to specific size
sudo lvreduce -L 10G /dev/vg_data/lv_home

# Reduce with filesystem resize
sudo lvreduce -L 10G -r /dev/vg_data/lv_home

⚠️ Warning: Always shrink the filesystem BEFORE reducing LV size to avoid data loss!

lvresize - Resize Logical Volume

Change the size of a logical volume (extend or reduce).

# Resize to specific size
sudo lvresize -L 15G /dev/vg_data/lv_home

# Resize with filesystem adjustment
sudo lvresize -L 15G -r /dev/vg_data/lv_home

lvremove - Remove Logical Volume

Delete a logical volume.

# Remove LV
sudo lvremove /dev/vg_data/lv_home

# Force removal without confirmation
sudo lvremove -f /dev/vg_data/lv_home

lvscan - Scan for Logical Volumes

Scan all disks for logical volumes.

# Scan for all LVs
sudo lvscan

# Verbose output
sudo lvscan -v

Filesystem Operations

After creating logical volumes, you need to format them with a filesystem and mount them. For a deeper understanding of Linux filesystems, see our Linux Filesystem cheatsheet.

Create Filesystem

# Create ext4 filesystem
sudo mkfs.ext4 /dev/vg_data/lv_home

# Create XFS filesystem
sudo mkfs.xfs /dev/vg_data/lv_data

# Create ext4 with label
sudo mkfs.ext4 -L "Home" /dev/vg_data/lv_home

Mount Logical Volume

# Create mount point
sudo mkdir -p /mnt/home

# Mount LV
sudo mount /dev/vg_data/lv_home /mnt/home

# Verify mount
df -h /mnt/home

Permanent Mount (fstab)

# Add to /etc/fstab for automatic mounting
sudo nano /etc/fstab

# Add this line:
/dev/vg_data/lv_home  /mnt/home  ext4  defaults  0  2

# Or use UUID (recommended)
# Find UUID
sudo blkid /dev/vg_data/lv_home

# Add to fstab:
UUID=xxxx-xxxx-xxxx  /mnt/home  ext4  defaults  0  2

# Test fstab
sudo mount -a

Resize Filesystem

# Resize ext4 filesystem (after extending LV)
sudo resize2fs /dev/vg_data/lv_home

# Resize XFS filesystem (must be mounted)
sudo xfs_growfs /mnt/home

# Shrink ext4 filesystem (unmount first)
sudo umount /mnt/home
sudo e2fsck -f /dev/vg_data/lv_home
sudo resize2fs /dev/vg_data/lv_home 10G
sudo mount /dev/vg_data/lv_home /mnt/home

💡 Note: XFS filesystems cannot be shrunk, only extended.

LVM Snapshots

LVM snapshots provide point-in-time copies of logical volumes, useful for backups and testing. Combine with tar archives for complete backup solutions.

Create Snapshot

# Create snapshot (allocate space for changes)
sudo lvcreate -L 5G -s -n lv_home_snap /dev/vg_data/lv_home

# Create snapshot using percentage
sudo lvcreate -l 20%ORIGIN -s -n lv_home_snap /dev/vg_data/lv_home

💡 Tip: Snapshot size should be 20-30% of the original volume for most use cases.

Mount Snapshot

# Create mount point
sudo mkdir -p /mnt/snap

# Mount snapshot (read-only recommended)
sudo mount -o ro /dev/vg_data/lv_home_snap /mnt/snap

# Mount read-write (for testing)
sudo mount /dev/vg_data/lv_home_snap /mnt/snap

Check Snapshot Usage

# View snapshot status
sudo lvs -a -o +lv_size,data_percent,snap_percent

# Display detailed snapshot info
sudo lvdisplay /dev/vg_data/lv_home_snap

Restore from Snapshot

# Unmount the original volume
sudo umount /mnt/home

# Merge snapshot (restore)
sudo lvconvert --merge /dev/vg_data/lv_home_snap

# If volume is active, merge happens on next activation
# Reboot or deactivate/reactivate the LV
sudo lvchange -an /dev/vg_data/lv_home
sudo lvchange -ay /dev/vg_data/lv_home

# Remount
sudo mount /dev/vg_data/lv_home /mnt/home

Remove Snapshot

# Unmount snapshot
sudo umount /mnt/snap

# Remove snapshot
sudo lvremove /dev/vg_data/lv_home_snap

Extend Snapshot

# If snapshot is filling up, extend it
sudo lvextend -L +2G /dev/vg_data/lv_home_snap

⚠️ Warning: If a snapshot fills up completely, it becomes invalid and unusable!

Common LVM Workflows

1. Complete LVM Setup (New Disk)

# Step 1: Create partition (optional, can use entire disk)
sudo fdisk /dev/sdb
# Create new partition, type 8e (Linux LVM)

# Step 2: Create Physical Volume
sudo pvcreate /dev/sdb1

# Step 3: Create Volume Group
sudo vgcreate vg_data /dev/sdb1

# Step 4: Create Logical Volume
sudo lvcreate -L 50G -n lv_home vg_data

# Step 5: Create filesystem
sudo mkfs.ext4 /dev/vg_data/lv_home

# Step 6: Mount
sudo mkdir -p /mnt/home
sudo mount /dev/vg_data/lv_home /mnt/home

# Step 7: Add to fstab for permanent mount
echo "/dev/vg_data/lv_home  /mnt/home  ext4  defaults  0  2" | sudo tee -a /etc/fstab

2. Extend Logical Volume (Add Space)

# Check available space in VG
sudo vgs

# Extend LV
sudo lvextend -L +20G /dev/vg_data/lv_home

# Resize filesystem (ext4)
sudo resize2fs /dev/vg_data/lv_home

# OR do both in one command
sudo lvextend -L +20G -r /dev/vg_data/lv_home

# For XFS (must be mounted)
sudo xfs_growfs /mnt/home

3. Add New Disk to Existing Volume Group

# Create PV on new disk
sudo pvcreate /dev/sdc1

# Add to existing VG
sudo vgextend vg_data /dev/sdc1

# Verify
sudo pvs
sudo vgs

# Now you have more space to create/extend LVs
sudo lvextend -L +50G /dev/vg_data/lv_home
sudo resize2fs /dev/vg_data/lv_home

4. Move Data Between Physical Volumes

# Move all data from one PV to others in the same VG
sudo pvmove /dev/sdb1

# Move to specific PV
sudo pvmove /dev/sdb1 /dev/sdc1

# Check progress
sudo pvmove --abort  # To cancel if needed

# After move, remove PV from VG
sudo vgreduce vg_data /dev/sdb1

# Remove PV label
sudo pvremove /dev/sdb1

5. Backup with Snapshot

# Create snapshot
sudo lvcreate -L 5G -s -n lv_home_backup /dev/vg_data/lv_home

# Mount snapshot
sudo mkdir -p /mnt/backup
sudo mount -o ro /dev/vg_data/lv_home_backup /mnt/backup

# Perform backup
sudo rsync -avz /mnt/backup/ /backup/home/

# OR create tar backup
sudo tar czf /backup/home-$(date +%Y%m%d).tar.gz -C /mnt/backup .

# Cleanup
sudo umount /mnt/backup
sudo lvremove /dev/vg_data/lv_home_backup

6. Complete LVM Removal

# Unmount all LVs
sudo umount /mnt/home

# Remove from fstab
sudo nano /etc/fstab  # Remove the line

# Remove Logical Volumes
sudo lvremove /dev/vg_data/lv_home

# Remove Volume Group
sudo vgremove vg_data

# Remove Physical Volumes
sudo pvremove /dev/sdb1

# Optional: Zero out partition
sudo dd if=/dev/zero of=/dev/sdb1 bs=1M count=100

Troubleshooting

LVM Not Detecting Volumes

# Scan for all volumes
sudo pvscan
sudo vgscan
sudo lvscan

# Rebuild cache
sudo pvscan --cache
sudo vgscan --mknodes

# Activate all volume groups
sudo vgchange -ay

Volume Group Not Found

# Check if VG is inactive
sudo vgs -a

# Activate VG
sudo vgchange -ay vg_data

# Check for missing PVs
sudo vgdisplay vg_data | grep -i missing

Cannot Remove Physical Volume

# Check if PV is in use
sudo pvs -o pv_name,vg_name,pv_used

# Move data off the PV first
sudo pvmove /dev/sdb1

# Then reduce from VG
sudo vgreduce vg_data /dev/sdb1

# Now remove
sudo pvremove /dev/sdb1

Snapshot Filled Up

# Check snapshot usage
sudo lvs -a -o +snap_percent

# If under 100%, extend it
sudo lvextend -L +2G /dev/vg_data/lv_home_snap

# If at 100%, snapshot is invalid
# Remove and recreate
sudo lvremove /dev/vg_data/lv_home_snap
sudo lvcreate -L 10G -s -n lv_home_snap /dev/vg_data/lv_home

Filesystem Won't Resize

# For ext4, check filesystem first
sudo umount /mnt/home
sudo e2fsck -f /dev/vg_data/lv_home
sudo resize2fs /dev/vg_data/lv_home
sudo mount /dev/vg_data/lv_home /mnt/home

# For XFS, must be mounted
sudo mount /dev/vg_data/lv_home /mnt/home
sudo xfs_growfs /mnt/home

View LVM Logs

# Check system logs for LVM issues
sudo journalctl -u lvm2* -n 100

# Check dmesg for disk/LVM errors
sudo dmesg | grep -i lvm

# Verbose LVM commands
sudo pvs -vvv
sudo vgs -vvv
sudo lvs -vvv

Need more diagnostic capabilities? Explore our server management tools for advanced troubleshooting.

Best Practices

  • • Always backup important data before LVM operations
  • • Use descriptive names for VGs and LVs (e.g., vg_data, lv_home)
  • • Monitor snapshot usage to prevent them from filling up
  • • Leave 10-20% free space in VGs for flexibility
  • • Document your LVM structure and naming conventions
  • • Test restore procedures regularly
  • • Use -r flag with lvextend to auto-resize filesystem
  • • Always check available space before extending: vgs

Related Cheatsheets

Linux Filesystem

Storage fundamentals and filesystem types

Linux Commands

Essential command-line operations

Linux Admin Tips

System management best practices

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Tar Archives

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Linux Hardening

Security best practices for storage
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