Mastering LVM on Linux: Step‑by‑Step Guide to Create, Extend, and Manage Logical Volumes

1. Introduction to LVM

LVM (Logical Volume Manager) adds a flexible abstraction layer between physical disks and file systems, allowing dynamic resizing of partitions without data loss. It groups multiple disks into volume groups (VG) and creates logical volumes (LV) that can be resized on demand.

2. Test Environment

Platform: VMware Workstation 17 Pro Guest OS: Rocky Linux 8.9

3. Practical Examples

3.1 Create Physical Volume (PV)

parted /dev/sdb print          # view disk info
pvcreate /dev/sdb               # create PV

Verify PV status:

pvscan
pvs
pvdisplay /dev/sdb

3.2 Create Volume Group (VG)

vgcreate vgtest /dev/sdb        # create VG named vgtest

Check VG status:

vgscan
vgs
vgdisplay vgtest

3.3 Create Logical Volume (LV)

lvcreate -l 100%FREE vgtest -n lvtest   # allocate all VG space to LV

View LV information:

lvscan
lvs
lvdisplay vgtest/lvtest

3.4 Extend Logical Volume

Increase LV size by 200 MiB: lvextend -L +200M vgtest2/lvtest2 Or extend by a number of extents: lvextend -l +25 vgtest2/lvtest2 Allocate all free space:

lvextend -l +100%FREE vgtest2/lvtest2

3.5 Mount and Persistently Mount LV

mkfs.xfs /dev/vgtest2/lvtest2          # create XFS filesystem
mkdir /data
mount /dev/vgtest2/lvtest2 /data
blkid /dev/vgtest2/lvtest2               # get UUID
# Add to /etc/fstab for permanent mount
UUID="544fae3b-7d08-4090-a6a7-aa5bcc4d9be0" /data xfs defaults 0 0

3.6 Expand VG with New Disks

Rescan SCSI hosts to detect new disks, then create a new PV and extend the VG:

echo "- - -" > /sys/class/scsi_host/host0/scan
# repeat for host1, host2
pvcreate /dev/sdf
vgextend vgtest2 /dev/sdf

After extending the VG, enlarge the LV and the filesystem:

lvextend -l +100%FREE vgtest2/lvtest2
xfs_growfs /dev/vgtest2/lvtest2

3.7 Resize LV and Filesystem in One Step

pvcreate /dev/sdg
vgextend vgtest2 /dev/sdg
lvextend -L +5G -r vgtest2/lvtest2   # extend LV by 5 GiB and resize XFS automatically

The article demonstrates the full lifecycle of LVM management: creating PVs, VGs, LVs, extending them, mounting, and handling storage growth without rebooting.