Hi guys!
I already posted about Hang Analyze (part1, part2) and ASHDUMP. Now, in the same ‘package’, let me show you about SYSTEMSTATE DUMP.

Systemstate is basically made by the process state for all process in instance (or instances) at the time the systemstate is called.
Through a systemstate it’s possible to identify enqeues, rowcache locks, mutexes, library cache pins and locks, latch free situations, and other kind of chains.

It’s a good tool to add in a SR, but it’s quite hard to habituate on reading/interpreting the file. To undertand exactly how to read a systemstate I’d recommend you the best: Read the manual!
The doc Reading and Understanding Systemstate Dumps (Doc ID 423153.1) has a very good explanation with examples, I’m not able to to it better. 🙂

What I can do is share about the SYSTEMSTATE levels. I had some difficult to find it…
But before I show how you can do it, it’s important to mention that Oracle does not recommend you to use ‘numeric events’ without a SR (MOS), according to Note: 75713.1.