*This is an abstract only. No full paper is available for this abstract.* The primary objective of a rock support system is to maintain the integrity of excavations in rock and ensure the safety of personnel and equipment. A well-designed and implemented rock support system should still be able to provide support in the event of damage to some of its components that can result in system degradation but not failure. This may not be the case where a support system fails due to the presence of a weak link' that can be caused by impact loads, overload, manufacturing flaws or corrosion. The long-term effectiveness of rock support systems can be quantified by the use of performance metrics.Fault tolerance or graceful degradation is the property that enables a system to continue operating properly in the event of the failure of (or one or more faults within) some of its components. If its operating quality decreases at all, the decrease is proportional to the severity of the failure, as compared to a naively designed system in which even a small failure can cause total breakdown. Fault tolerance is particularly sought after in high-availability or life-critical systems.A fault-tolerant design enables a system to continue its intended operation, possibly at a reduced level, rather than failing completely when some part of the system fails. The term is most commonly used to describe computer systems designed to remain more or less fully operational, with perhaps a reduction in throughput or an increase in response time, in the event of some partial failure. That is, the system as a whole is not stopped due to problems either in the hardware or the software. An example in another field is a motor vehicle designed so that it will continue to be drivable if one of the tires is punctured. A structure is able to retain its integrity in the presence of damage due to causes such as fatigue, corrosion, manufacturing flaws or impact.CITATION:Hadjigeorgiou, J, 2014. Rock support system degradation and performance metrics, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 17-18 (The Australasian Institute of Mining and Metallurgy: Melbourne).