JSI Tip 10057. The User Mode Process Dumper (userdump) dumps any running Win32 processes memory image on the fly, without attaching a debugger, or terminating target processes.

The Microsoft Download Center User Mode Process Dumper Version 8.0 page contains the following overview:

The User Mode Process Dumper (userdump) dumps any running Win32 processes memory image (including system processes such as csrss.exe, winlogon.exe, services.exe, etc) on the fly, without attaching a debugger, or terminating target processes. Generated dump file can be analyzed or debugged by using the standard debugging tools.

The userdump generates dump file by several triggers;