I have created a hadoop cluster with two nodes (A and B). 'A' act both as namenode and datanode, and 'B' act as datanode only. With this setup, I could store, read files. Now, I added one more datanode 'C' and relieved 'A' from datanode duty. This means, 'A' act only as namenode, and both B and C act as datanodes. Now, I tried to create a directory, it says

' org.apache.hadoop.hdfs.server.namenode.SafeModeException: Cannot create directory Name node is in safe mode'
Can someone tell me why the namenode now is in safe mode?

With thanks and regards
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