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Welcome to our in-depth guide on configuring and managing LVM (Logical Volume Manager) storage in Linux. LVM provides dynamic volume resizing, flexible disk pooling, and snapshot capabilities, making it a powerful tool for system administrators.

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What You’ll Learn

  • Installing LVM utilities
  • Key LVM components: PV, VG, LV, PE
  • Creating Physical Volumes (PV)
  • Building and extending Volume Groups (VG)
  • Allocating and resizing Logical Volumes (LV)
  • Formatting and resizing filesystems
  • Common commands and handy tips

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Prerequisites

We’ve attached three new 5 GiB virtual disks to our CentOS VM. If you haven’t installed the LVM tools yet, run: 
sudo dnf install lvm2
Most LVM operations require root privileges. Prepend sudo or switch to the root user before proceeding.

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LVM Abbreviations

ResourceDescriptionCommand Prefix
Physical Volume (PV)A disk or partition managed by LVMpv*
Volume Group (VG)A pool of one or more PVsvg*
Logical Volume (LV)A virtual partition carved from a VGlv*
Physical Extent (PE)The smallest allocation unit in LVMn/a

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1. Creating Physical Volumes (PV)

Physical Volumes are the foundation of LVM. You can use entire disks or partitions.
  1. Scan for available disks and existing PVs: 
    sudo lvmdiskscan
    Sample output: 
    /dev/sda1  [   1.00 GiB]
/dev/sda2  [ <19.00 GiB] LVM physical volume
/dev/sdb1  [   4.00 GiB]
/dev/sdc   [   5.00 GiB]
/dev/sdd   [   5.00 GiB]
/dev/sde   [   5.00 GiB]
3 disks
1 LVM physical volume
  2. Initialize /dev/sdc and /dev/sdd as new PVs: 
    sudo pvcreate /dev/sdc /dev/sdd
  3. Verify all PVs: 
    sudo pvs

      PV         VG         Fmt  Attr PSize   PFree
  /dev/sda2  cs         lvm2 a--  <19.00g    0
  /dev/sdc   lvm2 ---   5.00g  5.00g
  /dev/sdd   lvm2 ---   5.00g  5.00g
PFree indicates unallocated space ready for LVs.

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2. Building a Volume Group (VG)

Volume Groups aggregate one or more PVs into a single storage pool.
  1. Create a VG named my_volume: 
    sudo vgcreate my_volume /dev/sdc /dev/sdd

    Volume group "my_volume" successfully created
  2. To extend the VG later, initialize another PV: 
    sudo pvcreate /dev/sde
  3. Add it to my_volume: 
    sudo vgextend my_volume /dev/sde
  4. List all VGs: 
    sudo vgs

      VG          #PV #LV #SN Attr   VSize   VFree
  cs           1   2   0 wz--n  <19.00g    0
  my_volume    3   0   0 wz--n  14.99g 14.99g

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Removing a PV from a VG

  1. Detach /dev/sde: 
    sudo vgreduce my_volume /dev/sde
  2. Wipe its metadata: 
    sudo pvremove /dev/sde

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3. Allocating Logical Volumes (LV)

Logical Volumes are like partitions within a VG.
  1. Create a 2 GiB LV called partition1: 
    sudo lvcreate --size 2G --name partition1 my_volume
  2. Create a 6 GiB LV called partition2: 
    sudo lvcreate --size 6G --name partition2 my_volume
  3. View all LVs: 
    sudo lvs

      LV         VG         Attr       LSize
  partition1 my_volume -wi-a----- 2.00g
  partition2 my_volume -wi-a----- 6.00g
  4. Check remaining VG space: 
    sudo vgs

      VG         #PV #LV #SN Attr   VSize   VFree
  my_volume   2   2   0 wz--n-  9.99g  1.99g

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4. Resizing Logical Volumes

LVM data is allocated in Physical Extents (PE). You can grow or shrink LVs by adjusting their extents.

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Grow to Fill Free Space

Expand partition1 to consume all free extents: 
sudo lvresize --extents +100%FREE /dev/my_volume/partition1

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Shrink Back

Reduce partition1 back to 2 GiB: 
sudo lvresize --size 2G /dev/my_volume/partition1
Shrinking a filesystem without shrinking the filesystem itself first can lead to data loss. Always unmount, run a filesystem check, and resize the filesystem before reducing an LV.

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5. Formatting the Filesystem

Before storing data, format your LV. For example, to use XFS: 
sudo mkfs.xfs /dev/my_volume/partition1

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6. Resizing with an Existing Filesystem

To grow both the LV and its filesystem in one command: 
sudo lvresize --resizefs --size 3G /dev/my_volume/partition1
Note: Not all filesystems support online shrinking. Check your filesystem’s documentation.

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7. Handy Tips & Resources

  • Browse the full LVM manual: 
    man lvm
  • Use tab-completion to explore subcommands: 
    vg↹↹
  • Always back up critical data before performing volume operations.

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