Document URL: https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux_atomic_host/7/html/managing_containers/managing_storage_with_docker_formatted_containers#overlay_graph_driver
Section Number and Name: 1.6. Overlay Graph Driver
Describe the issue:
There are a few variables unexplained in the documentation regarding overlay2 support for docker.
It seems overlay2 support is different than multipath, so if you specify the CONTAINER_ROOT_LV_NAME and CONTAINER_ROOT_LV_MOUNT_PATH variables, it will create a new logical volume for storing container images and container rootfs, otherwise, no new logical volume will be created and overlay2 will be setup on rootfs.
Suggestions for improvement:
Include proper documentation about how this works and different scenarios, as it is assumed it works like multipath (it will create the lv, etc. without needed those variables)
There is a related Bugzilla where you can find more information https://bugzilla.redhat.com/show_bug.cgi?id=1490910