This host is running in loop-lvm mode, which is not supported on production systems. This is indicated by the fact that the Data loop file and a Metadata loop file are on files under /var/lib/docker/devicemapper. These are loopback-mounted sparse files. For production systems, see Configure direct-lvm mode for production.

devicemapper supports 2 modes:
loop-lvm (only for dev)
direct-lvm (production ok)

docker info