DonYou are right that everything you saw in the logs are symptomsm, not root causes. Go back in dba_hist_active_sess_history aggregating sum(time_waited) by wait_class in minute slices for the affected period and find the first sign of things going awry.
Drill down and find the waits that A) touched the whole thing off and B) sustained the hang.
Don't know whose article/posting suggested changing PROCESSES, but that sure sounds like a shot in the dark to me. Oracle is heavily instrumented, and we should all use data before trying suggestions from Google. Because you didn't restart Oracle, all the ASH data should have been preserved in AWR.
Jeremiah Wilton ORA-600 Consulting http://www.ora-600.net Don Seiler wrote:
Running 10gR2 (10.2.0.2) on RHEL4 on 4 64-bit dual-core box. Earlier today users complained en masse about not being able to connect to the database. I got to a term and found that even trying to log in locally as sysdba was hanging. So in summary, there was hanging for everyone, it seemed to clear itself up. One post on Google suggested that the PROCESSES init parameter might be too low. Any other possibilities?