Unlike proprietary operating system environments, some end users expect to access and tinker-with the same UNIX system resources that are available to them on their UNIX workstations. This is especially true in engineering and scientific environments.
Open systems continue to be more widely used in critical business applications.
Customers expect these same systems to achieve ever higher availability requirements. Open systems environments, by their very nature, tend to support a vast array of diverse applications and application environments. This greatly increases the number of varied applications and configuration permutations which in turn increases the number of code paths and states that can be encountered. A system's ultimate reliability is limited by the reliability of its least reliable component. Applications in open systems environments often have access to critical system resources that when unintentionally misused can cause failure.