Title : Create a new OpenBSD partition from unused space
Author: Solène
Date  : 20 September 2018
Tags  : openbsd68 openbsd highlight

The default OpenBSD partition layout uses a pre-defined template. If
you have a disk more than 356 GB you will have unused space with the
default layout (346 GB before 6.4).

It's possible to create a new partition to use that space if you did
not modify the default layout at installation. You only need to start
**disklabel** with flag *-E** and type **a** to add a partition,
default will use all remaining space for the partition.

    # disklabel -E sd0
    Label editor (enter '?' for help at any prompt)
    > a
    partition: [m]
    offset: [741349952]
    size: [258863586]
    FS type: [4.2BSD]
    > w
    > q
    No label changes.

The new partition here is **m**. We can format it with:

    # newfs /dev/rsd0m

Then, you should add it to your **/etc/fstab**, for that, use the same
uuid as for other partitions, it would look something like

    52fdd1ce48744600.e /data ffs rw,nodev,nosuid 1 2

It will be auto mounted at boot, you only need to create the folder
/data. Now you can do

    # mkdir /data
    # mount /data

and **/data** is usable right now.

You can read [disklabel(8)](https://man.openbsd.org/disklabel.8) and
[newfs](https://man.openbsd.org/newfs.8) for more informations.