We found c1lsc, c1iscex, c1iscey, c1susvme, c1asc and c1sosvme are dead.
We turned off all watchdogs and turned off all lock of suspensions.
Then, I tried to reboot these machines from terminal, but I couldn't login to all of these machines.
So, we turned off and on key switches of these machines physically, and login to them to run startup scripts.
Then we turned on all watchdogs and restored all IFO.
Now they look like they are working fine.