Reliability-aware software architecture development has recently been gaining growing attention among software architects. This paper tackles the issue by introducing an ontology-based approach, called OntoArch, which is characterized by: 1) integration of software reliability engineering and software architecture design; 2) targeting reliability-aware software architecture development; and 3) OntoArch ontology in the context of software architecture design and software reliability engineering. The OntoArch approach is validated by applying the OntoArch approach to the development of a PIR (Personal Information Repository) system architecture.