Defining Survivability for Engineering Systems

This paper introduces an on-going doctoral research track on the role of survivability as an attribute in the design of complex system architectures. Survivability may be defined generally as the ability of a system to minimize the impact of a finite disturbance on value delivery, achieved through either the satisfaction of a minimally acceptable level of value delivery during and after a finite disturbance or the reduction of the likelihood or magnitude of a disturbance. While survivable design of physical system components is a well-understood practice that is best left to established domains, architecting for survivability is a poorly-understood, socio-technical challenge increasingly relevant to engineering systems. After describing the motivation for and the scope of the research, survivability is conceptualized as a meta-framework for robustness and changeability. Survivability includes both passive and active techniques which may manifest themselves in the physical, operational, and organizational design of engineering systems. Where passive survivability relies on the design principles of hardness, stealth, redundancy, and diversity to enable a system to resist a projected disturbance environment, active survivability embraces uncertainty in the projection of future disturbances by stressing architectural agility through the ability to regenerate, evolve, relocate, and retaliate.