Swapping requires a backing store.

交换需要一个后备存储器。

The backing store is commonly a fast disk .

后备存储器通常是一个高速磁盘。

They can also be purely in-memory objects with no backing store.

它们可以是一些纯粹的内存对象，只要不用于后备存储。

Registry and Repository uses a relational database as its backing store.

Registry and Repository 使用关系数据库作为其支持存储区。

That way, we can change the backing store without rewriting the service class.

这样，我们可以修改后台存储而不必重写服务类。