Was working on docker on a server, and on startup, I see Nov 29 10:58:27 dockerd-current:
time=”2017-11-29T10:58:27.612849959-05:00″ level=warning msg=”devmapper:
Usage of loopback devices is strongly discouraged for production use. Please use `–storage-opt dm.thinpooldev` or use `man docker` to refer to dm.thinpooldev section.”
Nov 29 10:58:27 dockerd-current:
time=”2017-11-29T10:58:27.655600686-05:00″ level=warning msg=”devmapper:
Base device already exists and has filesystem xfs on it. User specified filesystem will be ignored.”
The latter would explain the message my user’s job gave him when it tried to umount /
A bit of googling, and I see something called overlayFS can be used… but I know nothing about that, or how dangerous it is. Anyone got a pointed to something more than the minimal how to configure docker to use it?