Real Application Clusters (RAC) use a cache-to-cache block transfer mechanism
known as Cache Fusion to transfer read-consistent images of blocks from one instance
to another. RAC does this using high speed, low latency interconnects to satisfy remote
requests for data blocks.

RAC下的一致性读
1. RAC 系统采用缓存对缓存的数据块传输机制(Cache Fusion)在实例间传输满足读一致性的数据
块镜像