Summary: Benign Failure Models for Shared Memory \Lambda
Yehuda Afek y Michael Merritt z Gadi Taubenfeld y
November 13, 1995
This paper introduces two benign failure models for shared memory in distributed
systems, omissioncrash and eventualcrash. These models are of intermediate power
between the crash model and omission models of [JCT92]. (They exhibit more faulty
behaviors than crash and fewer than omission.) Unlike the crash model, omissioncrash
is shown to have universal, gracefullydegrading constructions. That is, for any integer
k, any shared object may be constructed from shared registers and consensus objects,
so that: (1) if no more than k of the components suffer omissioncrash failures, the
constructed object exhibits no failures, and (2) if more than k of the components suffer
omissioncrash failures, the constructed object exhibits omissioncrash failures.
Simple constructions also demonstrate that registers and consensus objects in the
(apparently) less benign eventualcrash model can be used to construct corresponding
objects in the omissioncrash model.
These results are cited as evidence that the omissioncrash failure model may
be an appropriate choice to consider in the formulation of a more extensive theory of
faulttolerant shared objects.
1 Benign failure models for shared memory