The SysRq facility is one of the best (and sometimes the only) way to determine what a machine is really doing. When triggered, SysRq will send a signal requesting some diagnostic information to the operating system kernel. This is most useful when a system appears to be "hung", and for diagnosing elusive, transient, kernel-related problems.
What is the "Magic" SysRq key?
Subscriber exclusive content
A Red Hat subscription provides unlimited access to our knowledgebase of over 48,000 articles and solutions.