Unless there is a reason not to, I recommend we move to overlay2, as I ran into a number of time sink issues on account of using overlay1. All that needs to be changed, is that systemd's Exec start needs to be:
ExecStart=/usr/bin/dockerd --storage-driver=overlay2 -H fd://
ExecStart=/usr/bin/dockerd --storage-driver=overlay -H fd://
That being said, is there a reason for using the outdated driver?