1. High availability hadoop2.x architecture
The core components of Hadoop1.x are two parts, HDFS and MapReduce. It becomes HDFS and Yarn in Hadoop2. There is no longer only one NameNode in the new HDFS, but there can be multiple ones. Each has the same function.
1. What is the status of the two NameNodes?
Dual Namenode high availability Hadoop cluster architecture:
One is in active state and the other is in standby state. When the cluster is running, only the NameNode in the active state is working normally, and the NameNode in the standby state is in the standby state, and the data of the NameNode in the active state is always synchronized. Once the NameNode in the active state cannot work, the NameNode in the standby state can be changed to the active state through manual or automatic switching, and it can continue to work. This is high reliability.
Hadoop1.x HDFS architecture:
