Now we have free space in the Volume Group, we can assign that to the Logical Volume mounted on /. You can check the size of the logical volume with the command lvdisplay

root@deskpro:~# lvdisplay
  --- Logical volume ---
  LV Path                /dev/ubuntu-vg/ubuntu-lv
  LV Name                ubuntu-lv
  VG Name                ubuntu-vg
  LV UUID                t2f071-1PHF-fYIb-mgId-5g8G-fF7V-ZPxTGp
  LV Write Access        read/write
  LV Creation host, time ubuntu-server, 2023-11-28 12:12:11 +0000
  LV Status              available
  # open                 1
  LV Size                <28.00 GiB
  Current LE             7167
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:0
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To grow the size of the logical volume, you need to use the command lvresize, specifying the amount you want to resize and the LV path. You can specify a specific size with the -L flag (i.e. -L +500M), or an extent with the -l flag (i.e. -l +100%FREE). In thie example, we will allocate all the space available to the logical volume:

root@deskpro:~# lvresize -l +100%FREE /dev/ubuntu-vg/ubuntu-lv 
  Size of logical volume ubuntu-vg/ubuntu-lv changed from <28.00 GiB (7167 extents) to <48.00 GiB (12287 extents).
  Logical volume ubuntu-vg/ubuntu-lv successfully resized.
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We can confirm that the logical volume has grown by checking lvdisplay again:

root@deskpro:~# lvdisplay
  --- Logical volume ---
  LV Path                /dev/ubuntu-vg/ubuntu-lv
  LV Name                ubuntu-lv
  VG Name                ubuntu-vg
  LV UUID                t2f071-1PHF-fYIb-mgId-5g8G-fF7V-ZPxTGp
  LV Write Access        read/write
  LV Creation host, time ubuntu-server, 2023-11-28 12:12:11 +0000
  LV Status              available
  # open                 1
  LV Size                <48.00 GiB
  Current LE             12287
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:0
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Growing the filesystem

So far, we have increased the size of the disk, grown the partition, grown the physical volume and grown the logical volume. The final step is to grow the filesystem.

The method to grow the filesystem depends on the type of filesystem used. You can find your filesystem by running the command df -Th to get the type.

root@deskpro:~# df -Th
Filesystem                        Type   Size  Used Avail Use% Mounted on
tmpfs                             tmpfs  392M  1.2M  391M   1% /run
/dev/mapper/ubuntu--vg-ubuntu--lv ext4    28G  6.7G   20G  26% /
tmpfs                             tmpfs  2.0G     0  2.0G   0% /dev/shm
tmpfs                             tmpfs  5.0M     0  5.0M   0% /run/lock
/dev/sda2                         ext4   2.0G  129M  1.7G   8% /boot
tmpfs                             tmpfs  392M  4.0K  392M   1% /run/user/1000
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The default filesystem that Ubuntu uses is ext4, which uses the command resize2fs. If you use another filesystem (such as xfs, btrfs etc), you will need to use the tool specifically for that filesystem.

If you are using ext4, run the command resize2fs with the LV path:

root@deskpro:~# resize2fs /dev/ubuntu-vg/ubuntu-lv
resize2fs 1.46.5 (30-Dec-2021)
Filesystem at /dev/ubuntu-vg/ubuntu-lv is mounted on /; on-line resizing required
old_desc_blocks = 4, new_desc_blocks = 6
The filesystem on /dev/ubuntu-vg/ubuntu-lv is now 12581888 (4k) blocks long.
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We can confirm that has applied by re-running df -h to confirm the filesystem has grown to the new disk size:

root@deskpro:~# df -h
Filesystem                         Size  Used Avail Use% Mounted on
tmpfs                              392M  1.2M  391M   1% /run
/dev/mapper/ubuntu--vg-ubuntu--lv   48G  6.7G   39G  15% /
tmpfs                              2.0G     0  2.0G   0% /dev/shm
tmpfs                              5.0M     0  5.0M   0% /run/lock
/dev/sda2                          2.0G  129M  1.7G   8% /boot
tmpfs                              392M  4.0K  392M   1% /run/user/1000
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You have now successfully grown your filesystem.