  Nowadays, the consequences of failure and downtime of distributed systems
have become more and more severe. As an obvious solution, these systems
incorporate protection mechanisms to tolerate faults that could cause systems
failures and system dependability must be validated to ensure that protection
mechanisms have been implemented correctly and the system will provide the
desired level of reliable service. This paper presents a systematic approach
for identifying (1) characteristic sets of critical system elements for
dependability testing (single points of failure and recovery groups) based on
the concept of layered networks; and (2) the most important combinations of
components from each recovery group based on a combinatorial technique. Based
on these combinations, we determine a set of test templates to be performed to
demonstrate system dependability.
