As far as I know the main way for manually creating mini kernel dumps is attaching a local debugger which can issue commands by using noninvasive methods of recording information (AFAIK) which doesn't lead to a system crash.
I'm unsure why it does it automatically though.
It can be created by running the kdbgctrl.exe found in the debugging tools for windows, it's used as a remote debugger control.
I'll need to look further into this.
