Are COTS Suitable for Building Distributed Fault-Tolerant Hard Real-Time Systems?

For economic reasons, a new trend in the development of distributed hard real-time systems is to rely on the use of CommercialO -The-Shelf (cots) hardware and operating systems. As such systems often support critical applications, they must comply with stringent realtime and fault-tolerance requirements. The use of cots components in distributed critical systems is subject to two fundamental questions: are cots components compatible with hard real-time constraints? are they compatible with fault-tolerance constraints? This paper gives the current status of the Hades project, aiming at building a distributed run-time support for hard real-time fault-tolerant applications on top of cots components. Thanks to our experience in the design of Hades, we can give some information on the compatibility between cots components and hard real-time and fault-tolerance constraints.