To aid the formal verification of fault-tolerant distributed protocols, we propose an approach that significantly reduces the costs of their model checking. These protocols often specify atomic, process-local events that consume a set of messages, change the state of a process, and send zero or more messages. We call such events quorum transitions and leverage them to optimize state exploration in two ways. First, we generate fewer states compared to models where quorum transitions are expressed by single-message transitions. Second, we refine transitions into a set of equivalent, finer-grained transitions that allow partial-order algorithms to achieve better reduction. We implement the MP-Basset model checker, which supports refined quorum transitions. We model check protocols representing core primitives of deployed reliable distributed systems, namely: Paxos consensus, regular storage, and Byzantine-tolerant multicast. We achieve up to 92% memory and 85% time reduction compared to model checking with standard unrefined single-message transitions.

No abstract

No abstract

No abstract

We present on-line tunable diagnostic and membership protocols for generic time-triggered (TT) systems to detect crashes, send/receive omission faults and network partitions. Compared to existing diagnostic and membership protocols for TT systems, our protocols do not rely on the single-fault assumption and also tolerate non fail-silent (Byzantine) faults. They run at the application level and can be added on top of any TT system (possibly as a middleware component) without requiring modifications at the system level. The information on detected faults is accumulated using a penalty/reward algorithm to handle transient faults. After a fault is detected, the likelihood of node isolation can be adapted to different system configurations, including configurations where functions with different criticality levels are integrated. All protocols are formally verified using model checking. Using actual automotive and aerospace parameters, we also experimentally demonstrate the transient fault handling capabilities of the protocols.