Just as a warning:
If you use LVM-snapshots better stop it for the root filesystem. If your root-filesystem is on an LVM and you have a snapshot on it, dracut will be unable to boot the system.

Instead you will fall into the dracut emergency console, which sadly misses vi (or any editor). Because to repair the system you need to delete the snapshot and to be able to delete it you need to edit lvm.conf.

This post started as a question, but during writing a colleague managed to bring up a small workaround to get the system bootable again:
* sed -i -e 's/locking_type = 4/locking_type =1/' /etc/lvm/lvm.conf
* then you are able to delete the snapshot.

then you can reboot the system and should have a working system again.

But why does the system fail to boot just because of a snapshot?