Resilient
可以容忍 故障 的特性称为韧性（也叫容错）。系统的 韧性 不是无限度的，往往根据需求、预算去实现一定的 韧性。
需要明确 故障 一定存在，最好的容错机制是阻止故障变为 失效。
Designing Data-Intensive Applications
Systems that anticipate faults and can cope with them are called fault-tolerant or resilient. The former term is slightly misleading: it suggests that we could make a system tolerant of every possible kind of fault, which in reality is not feasible.[1]
Designing Data-Intensive Applications
It is impossible to reduce the probability of a fault to zero; therefore it is usually best to design fault-tolerance mechanisms that prevent faults from causing failures.[2]