It looks like your filesystem inside the LVM isn't taking up the available space.
example 200GB LVM utilising half the disk, which is the default when you install ubuntu server for example.
vgdisplay
VG Size <199.00 GiB
Alloc PE / Size 25472 / 99.50 Gib
Free PE / Size 25471 / <99.50 GiB
lsblk
└─sda3 8:3 0 199G 0 part
└─ubuntu--vg-ubuntu--lv 253:0 0 99.5G 0 lvm
Find the path name of your LVM:
lvdisplay
Mine is /dev/ubuntu-vg/ubuntu-lv
You can allocate all free space to the existing space with this:
Obviosuly you should have a backup of your data before doing this.
lvextend -l +100%FREE /dev/ubuntu-vg/ubuntu-lv
After this completes check "vgdisplay" to verify the space has been allocated.
This is what it looks like after:
vgdisplay
VG Size <199.00 GiB
Alloc PE / Size 50943 / <199.00 GiB
Free PE / Size 0 / 0
The file system is still going to be the same size though, it needs to be extended too. Mine is EXT4.
Inspect:
df -hT
Filesystem Type Size Used Avail Use%
/dev/mapper/ubuntu--vg-ubuntu--lv ext4 98G 5.1G 88G 6%
Run resize2fs to expand the ext4 filesystem to fill the VG
resize2fs /dev/ubuntu-vg/ubuntu-lv
This is what is looks like after:
df -hT
Filesystem Type Size Used Avail Use%
/dev/mapper/ubuntu--vg-ubuntu--lv ext4 196G 5.1G 182G 3% /
My 200GB LVM is now completely utilised.