Here are some useful statements for generating trace files in your udump directory about various important Oracle files:
Get a dump of your controlfiles:
ALTER SESSION SET EVENTS 'IMMEDIATE TRACE NAME CONTROLF LEVEL 10';
Dump the headers for all your datafiles:
ALTER SESSION SET EVENTS 'IMMEDIATE TRACE NAME FILE_HDRS LEVEL 10';
Dump the headers of your redologs:
ALTER SESSION SET EVENTS 'IMMEDIATE TRACE NAME REDOHDR LEVEL 10';
Dump the system state:
ALTER SESSION SET EVENTS 'IMMEDIATE TRACE NAME SYSTEMSTATE LEVEL 10';