Managing Disk Space with LVM: A Comprehensive Guide

Working with LVM (Logical Volume Management) can simplify the process of managing disk space. This post will guide you through enlarging a disk in LVM, migrating a non-LVM file system to LVM, and migrating the root file system to LVM.

Enlarging a Disk in LVM

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Refer to this article for more information: Manage and Create LVM Partition Using vgcreate, lvcreate, and lvextend.

To enlarge an existing LVM:

1. Check if the new disk is detected using lsblk. If not, scan it with:

echo "- - -" > /sys/class/scsi_host/host<N=1,2,3,4...>/scan

2. Create a physical volume, extend the volume group, and extend the logical volume:

pvcreate <new_disk>
vgextend <vg> <new_disk>
lvextend -l +100%FREE -r <lvm>

3. Resize the file system:

   • For ext4, use resize2fs.
   • For xfs, use xfsgrow.

4. You should able to see the resize disk on

df -h

Migrating Non-LVM File System to LVM

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For example, if you want to move /var to LVM:

1. Create the LVM.
2. Mount it to a temporary location (e.g., /tmp/lvm).
3. Copy data from /var to the LVM:

rsync -avz /var/ /tmp/lvm/

4. Unmount it.
5. Update /etc/fstab with the new LVM.
   • Use UUID to reference the file system.
   • Find the UUID with blkid.

Refer to fstab documentation for more details.

Migrating Root File System to LVM

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Refer to Converting an Existing Root Filesystem to LVM Partition.

The steps are similar to migrating a non-LVM file system:

1. Repeat the steps of migrating Non-LVM File System
2. Perform additional steps:
   • chroot to update initrd.
   • Edit grub.conf with the new root.
3. Restart the system.

Following these steps will help you manage disk space using LVM, whether you need to enlarge a disk, migrate a non-LVM file system to LVM, or migrate the root file system to LVM.