Shutdown the database – doing it the dirty way

It’s the first time ever that I saw an issue like this: I got a call from a colleague in London that he can’t connect to the database anymore. So I also tried to connect with sqlplus to the dabase but it just hanged. When I looked at the system I saw that there were several session processes which using all the cpu power on the machine. When I asked him if anyone else is currently on the system (it’s a test box) he said that there is no one on the database anymore and I can do whatever I want. Ok, first of all I started to kill the session processes as I wasn’t able to connect to the database anymore. After I did that “top” showed me that the pmon process was using 100% of the cpus. Nothing particular. Pmon is going to clean up the leftovers of the killed session processes. But after several minutes he still wasn’t finished. Ok, the problem was urgent and it was a test box. So what to do as next: Killing pmon – Oracle will shutdown the instance and recover from redo logs at start up. Of course that would have been to easy. Nothing happens just the cpu utilization was back to around 5%. In the alert log I could see that mman tried to kill the instance after pmon wasn’t anymore but the instance didn’t come down. So a little bit annoyed by the whole situation (wasn’t any of my databases which I administrate; I didn’t know WTF they did with/on the database and I had other issues to solve) I decided to do it on the really really dirty way and killed the smon process where the instance will definitely die. And that was what happend, the instance died and I was able to connect with sqlplus and restart the dabase. Unfotunately I hadn’t the time to investigate this issue further but it was the first time that I saw an issue like this were you aren’t able to shut down the database anymore except killing smon. Strange… I would like to know what they did with the system…