To dump the redo log headers:
ALTER SESSION SET EVENTS 'immediate trace name redohdr level 1';
Levels (circa Oracle 8.1.5) are:
| Level | Description |
| 1 | Dump redo log entry from control file |
| 2 | Level 1 + generic file header |
| 3 | Level 2 + log file header |
| 10 | Same as level 3 |
The following ORADEBUG command has the same effect:
ORADEBUG DUMP REDOHDR level