my colleague did a shutdown immediate, but the instance kept hanging... finally, he did a shutdown abort... and system responded that database shutdown successfully, he then startup the database but met the below
scumnt: failed to lock /oracle/sid/817_64/dbs/lkPM1 exclusive
ORA-09968: scumnt: unable to lock file
HP-UX Error: 13: Permission denied
ORA-1102 signalled during: alter database mount...
and to our horror, the ora_ processes did not die down gracefully, they are still there. so kill was issued but still these processes are still there, only 2, lgwr and chkpt.
finally, a restart of the unix box solved this issue.