If you have an external hard drive that is plugged in all the time but on one fine day you boot your system without the external hard drive and your system drops to a maintenance shell after looking through the syslog i.e journald you find out your system got into a loop trying to mount the external hard disk. So what is the solution?
It lies in the fstab file. In the /dev/sdb line add nofail,x-systemd.device-timeout=1
and do not set it to zero it will go into infinte loop.
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