Hi, i'm new to cloudera. i managed to install CDH  5 on my ubuntu machine. Now i'm trying to run the sample MapReduce program given in HUE. But i'm facing some problems. When i access the Namenode UI, i'm able to see the following.     Safe mode is ON. The reported blocks 0 needs additional 804 blocks to reach the threshold 0.9990 of total blocks 804. The number of live datanodes 0 has reached the minimum number 0. Safe mode will be turned off automatically once the thresholds have been reached.   And my datanode is completely down. i'm getting the following error in logs.   ERROR org.apache.hadoop.hdfs.server.datanode.DataNode Initialization failed for Block pool BP-188106977-192.168.1.83-1467389018936 (Datanode Uuid bb6abb9f-79f6-47ce-bb2d-af7ff290b32f) service to humworld-Inc/127.0.1.1:8022 Datanode denied communication with namenode because the host is not in the include-list: DatanodeRegistration(127.0.0.1, datanodeUuid=bb6abb9f-79f6-47ce-bb2d-af7ff290b32f, infoPort=50075, infoSecurePort=0, ipcPort=50020, storageInfo=lv=-56;cid=cluster117;nsid=988195820;c=0) at org.apache.hadoop.hdfs.server.blockmanagement.DatanodeManager.registerDatanode(DatanodeManager.java:943) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.registerDatanode(FSNamesystem.java:5079) at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.registerDatanode(NameNodeRpcServer.java:1156) at org.apache.hadoop.hdfs.protocolPB.DatanodeProtocolServerSideTranslatorPB.registerDatanode(DatanodeProtocolServerSideTranslatorPB.java:96) at org.apache.hadoop.hdfs.protocol.proto.DatanodeProtocolProtos$DatanodeProtocolService$2.callBlockingMethod(DatanodeProtocolProtos.java:29184) at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:617) at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:1073) at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2086) at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2082) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:422) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1693) at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2080) Sep 16, 8:01:26.387 PM INFO org.apache.hadoop.hdfs.server.datanode.DataNode Block pool BP-188106977-192.168.1.83-1467389018936 (Datanode Uuid bb6abb9f-79f6-47ce-bb2d-af7ff290b32f) service to humworld-Inc/127.0.1.1:8022 beginning handshake with NN Please help me with this.   Thanks, Karthi ... View more