Recently I had this situation. Freshly installed SLES 12.2 had a problem after reboot. For some strange reason, server entered emergency mode.
It looked like this.
It looked like this.
Welcome to emergency mode! After logging in,type "journalctl -xb" to view
system logs, "systemctl reboot" to reboot, "systemctl default" or ^D
to try again to boot into default mode.
Give root password for maintainence
(or type control-D to continue): 
After typing root password and executing systemctl default
everything
look OK. Network start to work, all services was up already. Reboot
also did the same thing, everything was perfect. But next time you need
to reboot, server was againg in emergency mode. So this had to be
solved.We update server, upgrade it to SLES 12.3, but problem was still there. One
thing I did notice when server was booting OK is this. Booting process
was finished and log in prompt was shown but ping was dead to server IP.
After a 5 seconds, EMC Networker agent started. This is showed by
printing nsrexecafter login prompt.After this process was started, ping start to run normally and server had network connectivity.Networker agent version was 8.2.2.Could this be the problem? I
deactive proccess to start after reboot. Reboot server. Server started
normally! Maybe this is a problem after all? We rebooted server 10 more
times. It started normally every time!
So
old version of Networker agent for some reason was entering in
emergency mode. This is pretty strange because, we are running several
SLES 12.2 on same hardware and we did not have this issues!
We installed latest EMC Networker agent 8.2.4, rebooted server for several times, everything looks OK. Server boot normally!