Persisting RancherOS state
You can run RancherOS in two ways. Boot from an ISO to memory or install on disk. There are some advantages of running it from ISO, like super easy update process. The downside is - by default, after reboot, you're going to loose all your images, settings and data. To fix that, you can persist the data by creating and mounting a partition. (documentation)
sudo mkfs.ext4 -L RANCHER_STATE /dev/sda
sudo reboot