Master Linux LVM: Create, Extend, Shrink, and Snapshot Volumes

Step 1: Partition Disks

Use fdisk /dev/sdb (repeat for /dev/sdc, /dev/sdd, /dev/sde) to create a single primary partition, set the type to 8e (Linux LVM), and write the table.

Step 2: Create Physical Volumes

pvcreate /dev/sd{b,c,d,e}1

Creates PVs on all four disks. pvs Shows each PV with size around 1004 MiB. pvdisplay /dev/sdb1 Displays detailed information for the first PV.

Step 3: Create Volume Group

vgcreate myvg /dev/sd{b,c,d}1

Creates volume group "myvg" with three PVs (default PE size 4 MiB). vgextend myvg /dev/sde1 Adds the fourth PV, increasing VG size. vgs Shows VG size and free space.

Step 4: Create Logical Volume

lvcreate -L 2G -n mylv myvg

Creates a 2 GiB logical volume named "mylv". lvdisplay /dev/myvg/mylv Shows LV attributes. mkfs.ext4 /dev/myvg/mylv Formats the LV with ext4. mkdir /mnt/mylv && mount /dev/myvg/mylv /mnt/mylv Mounts the LV; add an entry to /etc/fstab for permanent mounting.

Step 5: Extend the LV

lvextend -L 3G /dev/myvg/mylv

Expands the LV to 3 GiB. resize2fs /dev/myvg/mylv Resizes the filesystem to use the new space. df -h Shows the updated size.

Step 6: Reduce the LV (offline)

Unmount the LV, check the filesystem, shrink the filesystem, then shrink the LV.

umount /mnt/mylv

e2fsck -f /dev/myvg/mylv

resize2fs /dev/myvg/mylv 1G

lvreduce -L 1G /dev/myvg/mylv

After reduction, remount and verify with df -h.

Step 7: Create a Snapshot (read‑only)

mount -o remount,ro /dev/myvg/mylv /mnt/mylv

lvcreate -L 1G -n mylv-snap -p r -s /dev/myvg/mylv

mount -o remount,rw /dev/myvg/mylv /mnt/mylv

mount /dev/myvg/mylv-snap /mnt/snap

The snapshot is mounted read‑only.

Step 8: Remove LVM Objects

lvremove /dev/myvg/mylv-snap

pvremove /dev/sdb1

vgremove myvg

Use the corresponding man pages for details on removing PVs, VGs, and LVs.