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Resizing an ext4 Partition in Ubuntu

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A high level overview of the steps:

  1. Create a LiveCD
  2. Resize the Partition
  3. Resize the Logical Volume
  4. Resize the Filesystem

Recently I found an Ubuntu install I preformed had only allocated 100GB of a 1TB drive. Annoyed at either the installer or myself, I wanted to get it back.

1. Create a LiveCD

The Ubuntu install media can double as our LiveCD, and Etcher can write it to a thumb drive. Etcher supports Windows/MacOS/Linux, although Ubuntu's Startup Disk Creator can be used without requiring any 3rd party tools.

After you've booted into the LiveCD, ensure GParted is installed. If for some reason it's missing, use apt-get to install it.

2. Resize the Partition

Launching GParted, select the partition in question and resize it to fully utilize all available space. Be sure to "Apply All Operations", and once done you can boot back into your installed OS.

3. Resize the Logical Volume

Find the logical volume name. I only have one so it's rather obvious.

sudo vgs

VG        #PV #LV #SN Attr   VSize   VFree
ubuntu-vg   1   1   0 wz--n- 928.46g    0

We need to ensure there is available disk space to extend the logical volume.

sudo vgdisplay ubuntu-vg

  --- Volume group ---
  VG Name               ubuntu-vg
  ...
  VG Size               928.46 GiB
  PE Size               4.00 MiB
  Total PE              237686
  Alloc PE / Size       25600 / 100.00 GiB
  Free  PE / Size       212086 / 828.46 GiB
  VG UUID               wPiQTr-NEDl-fZwd-j5xA-psey-MHce-EBaaia

There's my missing 826GB's.

Now lvs can give us the logical volume path.

sudo lvs -o "lv_path,lv_dm_path"

  Path                     DMPath
  /dev/ubuntu-vg/ubuntu-lv /dev/mapper/ubuntu--vg-ubuntu--lv

With the DMPath /dev/mapper/ubuntu--vg-ubuntu--lv being the value we need.

Now we can resize it. As I want to make use of all the space, I'm providing +100%FREE.

sudo lvresize -l +100%FREE /dev/mapper/ubuntu--vg-ubuntu--lv

Repeating the check from earlier, we should now see zero free space.

sudo vgdisplay ubuntu-vg

  ...
  Alloc PE / Size       237686 / 928.46 GiB
  Free  PE / Size       0 / 0
  ...

4. Resize the Filesystem

sudo resize2fs /dev/mapper/ubuntu--vg-ubuntu--lv

Finally let's verify the space.

df -h

/dev/mapper/ubuntu--vg-ubuntu--lv  914G   53G  824G   6% /

Success.