Hey,

> guix system image -t qcow2 gnu/system/install.scm

So, I produced a qcow2 installation image this way, imported it in
DigitalOcean, then created a droplet out of it.

The qcow2 image is resized to the droplet disk image size, 25GiB in my
case, and appears as vda disk. There is also an empty vdb disk. In the
installer partitioning page, vda is hidden as this is the installation
device but vdb appears.

Trying to proceed with vdb fails and leads to the backtrace you sent
us. Two things here:

1. We should hide vdb as it is an empty drive, maybe by requiring a
minimal available space. Josselin, what do you think about it?

2. As the qcow2 installation image is also the main VM drive, it will be
hard to install Guix System this way. You might prefer to generate a
complete disk-image that suit your needs and use it directly on
DigitalOcean, as described here:
https://othacehe.org/hosting-a-blog-using-only-scheme.html.

Thanks,

Mathieu