How to use Logical Volume Management (LVM)

Logical Volume Management (LVM) in Linux allows for flexible disk management. Here’s a step-by-step guide to understand and use LVM:

Step-by-step guide on how to use LVM

Step1: Install LVM Tools

First, ensure that LVM tools are installed. On most Linux distributions, you can install them using:

sudo apt-get install lvm2 # For Debian/Ubuntu
sudo yum install lvm2 # For CentOS/RHEL

Step2: Create Physical Volumes (PVs)

Physical Volumes are the raw disks or disk partitions you will use in LVM.

• Decide which disk or partition to utilize. For example, /dev/sdb1.

sudo pvcreate /dev/sdb1

Step3: Create a Volume Group (VG)

Several physical volumes are combined into a single storage pool using volume groups

sudo vgcreate my_vg /dev/sdb1

• `my_vg` is the name of the volume group.

Step4: Create Logical Volumes (LVs)

Logical Volumes are created from the space in the Volume Groups.

sudo lvcreate -L 10G -n my_lv my_vg

• -L 10G specifies the size of the logical volume.
• -n my_lv sets the name of the logical volume.
• my_vg is the volume group from which space will be allocated.

Step5: Format the Logical Volume

Format the logical volume with a filesystem.

sudo mkfs.ext4 /dev/my_vg/my_lv

Step6: Mount the Logical Volume

Make a mount point, then mount the volume that makes sense.

sudo mkdir /mnt/my_mount
sudo mount /dev/my_vg/my_lv /mnt/my_mount

Step7: Configure Auto-Mounting

To ensure the logical volume mounts automatically at boot, add it to /etc/fstab.

echo ‘/dev/my_vg/my_lv /mnt/my_mount ext4 defaults 0 2’ | sudo tee -a /etc/fstab

***Common LVM Operations***

Step8: Extend a Logical Volume

First, extend the logical volume, then resize the filesystem.

sudo lvextend -L +5G /dev/my_vg/my_lv
sudo resize2fs /dev/my_vg/my_lv

• -L +5G extends the logical volume by 5 GB.

Step9: Reduce a Logical Volume

First, reduce the filesystem, then the logical volume.

sudo umount /mnt/my_mount
sudo e2fsck -f /dev/my_vg/my_lv
sudo resize2fs /dev/my_vg/my_lv 10G
sudo lvreduce -L 10G /dev/my_vg/my_lv
sudo mount /dev/my_vg/my_lv /mnt/my_mount

• Make sure to back up data before reducing to avoid data loss.

Step10: Remove a Logical Volume

sudo umount /mnt/my_mount
sudo lvremove /dev/my_vg/my_lv

Step11: Remove a Volume Group

sudo vgremove my_vg

Step12: Remove a Physical Volume

sudo pvremove /dev/sdb1

         *** LVM Overview ***

• Physical Volumes (PVs): Raw disks or partitions.
• Volume Groups (VGs): Pools of storage from PVs.
• Logical Volumes (LVs): Flexible storage units created from VGs.
• Benefits: Resize volumes, snapshots, flexible storage management. *** Example Scenario ***

1. Add a new disk: /dev/sdc
2. Create PV: pvcreate /dev/sdc
3. Extend VG: vgextend my_vg /dev/sdc
4. Extend LV: lvextend -L +10G /dev/my_vg/my_lv
5. Resize filesystem: resize2fs /dev/my_vg/my_lv

Read More Tutorials: How to use Logical Volume Management (LVM)

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