521.You notice that a job in a chain has not completed on a nonconstrained RAC database. Which of these are valid reasons why that might occur?
A. The job priority is 1 and the resource consumer group CPU emphasis allocation is a low percentage.
B. The job affinity is to a service and one node in that service is unavailable.
C. The job affinity is to an instance and that instance is unavailable.
D. There is no service affinity.
E. None of the above.
Answer: C

您会注意到在一个非约束的RAC数据库中，一个链中的作业还没有完成。下面这些哪一个是可能发生有效的原因？

C、作业和一个实例有密切关系，该实例不可用。

Since we‘ve established that the RAC is not performance constrained, option A is not valid—if the resource group were not able to obtain adequate CPU, this might be a valid answer. Option B is not correct because service affinity guarantees that if one instance in the service is available, the Scheduler will attempt to use it to run the job. If there is no service or instance affinity, the Scheduler will attempt to balance the load across surviving nodes.
既然我们已经确定RAC没有性能约束，选项A不是有效--如果资源组无法获得足够的CPU，这可能是一个有效的答案。
选项B是不正确的，因为服务的亲和力保证如果在服务中的一个实例，调度会尝试用它来运行作业，如果没有服务或实例的亲和力，调度会尝试幸存的节点之间的负载平衡。
Jobs can be defined with a service affinity (they should run on a specific service) as opposed to an instance affinity (they should run on a specific instance). If a job is assigned to a service consisting of two instances, even if one instance is down, the other can execute the job normally.