On the completion time distribution for tasks that must restart from the beginning if a failure occurs

Abstract

For many systems, failure is so common that the design choice of how to deal with it may have a significant impact on the performance of the system. There are many specific and distinct failure recovery schemes, but they can be grouped into three broad classes: RESUME , also referred to as preemptive resume (prs), or check-pointing; REPLACE , also referred to as preemptive repeat different (prd); and RESTART , also referred to as preemptive repeat identical (pri). The following describes the three recovery schemes: (1) RESUME: when a task is fails, it knows exactly where it stops, and can continue from that point when allowed to resume; (2) REPLACE: given a task fails, then when it begins processing again, it starts with a brand new task sampled from the same task time distribution; and, (3) RESTART: When a task fails, it loses all that it had acquired to up to that point and must start anew when upon continuing later. This is distinctly different from (2) since the task must run at least as long as it did before it failed, whereas a new sample, selected at random, might run for a shorter or longer time.