In this paper, scheduling resiliency is analyzed, defined as the deterioration of the performance measure used in the scheduling process after a disruption occurs and a reaction method has been applied to respond to this disruption. The unrelated parallel machines scheduling problem with makespan objective is considered, and a machine breakdown occurs before the schedule is executed and cannot be repaired. Two reaction methods are compared: Rescheduling all jobs on the remaining machines (named as rescheduling problem); or freezing the scheduled jobs on the operational machines, and only scheduling those assigned to the down machine (named as availability problem). Results show that, in low-variability scenarios the deterioration of the objective function by the availability problem has no statistically significant differences compared to the rescheduling problem, requiring negligible computational times. These findings imply that, in specific scenarios, the frozen policy can be an effective approach for achieving resilience in manufacturing scheduling.