This paper discusses the stability of a feasible pre-run-time schedule for
a transient overload introduced by processes re-execution during an error r
ecovery action. It shows that the stability of a schedule strictly tuned to
meet hard deadlines is very small, invalidating thus backward error recove
ry. However, the stability of the schedule always increases when a real-tim
e process is considered as having a nominal and a hard deadline separated b
y a non-zero grace time. This is true for sets of processes having arbitrar
y precedence and exclusion constraints, and executed on a single or multipr
ocessor based architecture. Grace time is not just the key element for the
realistic estimation of the timing constraints of real-time error processin
g techniques. It also allows backward error recovery to be included in very
efficient pre-run-time scheduled systems when the conditions stated in thi
s paper are satisfied. This is a very important conclusion, as it shows tha
t fault-tolerant hard real-time systems do not have to be extremely expensi
ve and complex.