Hang Analyze and System State Dumps.

Oracle support request hang analysis and system state dumps when rasing SR. 

One 10.1 or higher versions login as

sqlplus -prelim / as sysdba

To do a hanganalyze

oradebug setmypid;
oradebug unlimit;
oradebug hanganalyze 3

Wait 60 - 90 seconds and run the last command again to identify the process state changes.

To get a systemstate dump

oradebug setmypid;
oradebug unlimit;
oradebug dump systemstate 266

Wait 60 - 90 seconds and run again to identify the system state changes. 
If it is taking too long then cancel and run with level 258.
One a cluster environment use

oradebug -g all hanganalyze 3

for hang analyze and

oradebug -g all dump systemstate 266

for system state dumps.