In this talk, we share our experience on designing and implementing a next-generation, scale-out architecture for HDFS. Particularly, we implement the namespace on top of a key-value store. Key-value stores are highly scalable and can be scaled out on demand. Our current prototype shows that under the new architecture the namespace of HDFS scales 10x better than the current generation with no performance loss, demonstrating that HDFS is capable of storing billions of files using the current hardware.