Not your everyday task, yet, when nothing else you could do with a database that won’t start, give it a try. If you have valid Oracle support, then execute only after Oracle confirms.
Please note, there are no guarantees that using the “_ALLOW_RESETLOGS_CORRUPTION” hidden parameter will bring your database up and running. For example, I have made several attempts to duplicate a database in the same machine, few of the exercises were like following:
At home, I copied .dbf files from a live database and created a new database using the “_ALLOW_RESETLOGS_CORRUPTION” which was successful, when the same approach failed without any hopes on my work laptop where I have the same 10.2.0.3 to 126.96.36.199 upgraded instance.
Other hand whenever I copied the .dbf files from a shutdown database and tried to create a standby database, it always succeeded with “alter database open resetlogs”
So, don’t be over confident about recovering a database using “another” hidden parameter. If you are lucky, you may, on the other hand ONLY a proper backup will help you to recover from a significant crash.
So, start backing up your database on regular intervals. I suggest RMAN with archivelogs which helps you to backup the database without downtime.