Managing LVM in Linux

Part 1) Logical Volume Management (LVM) pools physical storage for flexible disk management.

1. Diagram Breakdown

• Physical Storage: Raw disks (/dev/sda and /dev/sdb).
• Physical Volumes (PV): Initialized disks formatted for LVM.
• Volume Group (VG): Combined pool (vg_data totaling 1.5TB).
• Logical Volumes (LV): Partitions (home, root, var) cut from the pool.

2. Practical Commands

Step 1: Create PVs Initialize the partitions for LVM use.

pvcreate /dev/sda1 /dev/sdb1

Step 2: Create VG Combine the PVs into a single pool named vg_data.

vgcreate vg_data /dev/sda1 /dev/sdb1

Step 3: Create LVs Carve out specific sizes from the volume group.

lvcreate -L 500G -n home vg_data
lvcreate -L 250G -n root vg_data
lvcreate -L 100G -n var vg_data

Step 4: Format & Mount Format with a file system and mount to directories.

mkfs.ext4 /dev/vg_data/home
mount /dev/vg_data/home /home

2) Make your LVM partitions permanent across reboots and learn how to scale storage dynamically.

1. Permanent Mounts via /etc/fstab

To ensure your logical volumes automatically mount at boot, add them to /etc/fstab.

Open the file in a text editor:

sudo nano /etc/fstab

Append the following lines to the bottom of the file:

/dev/vg_data/home  /home  ext4  defaults  0  2
/dev/vg_data/root  /      ext4  defaults  0  1
/dev/vg_data/var   /var   ext4  defaults  0  2

Test your setup to avoid boot errors:

sudo mount -a

2. Dynamically Resize Storage

The main advantage of LVM is resizing volumes on the fly without unmounting.

Expand a Logical Volume Add 50GB of extra space to your /home partition instantly:

lvextend -L +50G /dev/vg_data/home

Resize the Filesystem Grow the underlying filesystem to fill the newly allocated space.

For ext4 filesystems:

resize2fs /dev/vg_data/home

For XFS filesystems:

xfs_growfs /home