System Hang, Freeze, or Lockup - Root Cause Analysis (RCA) is Needed for the Unresponsive Server

Issue

My Red Hat Enterprise Linux system hung and is inaccessible and/or already existing sessions froze and became unresponsive to any commands or user action.

The server may or may not still respond to ping attempts, but the system is otherwise blocked from using ssh, terminal commands, and/or directly through the console.

System hangs are frustrating for end users and admins alike. They can occur seemingly without warning or happen over time as an apparent performance problem that gets worse and worse until the system slowly grinds to a halt. Some hangs aren't true hangs at all, but rather present as pauses in which the system appears to hang and stops responding for a period of time before recovering and working again on its own.