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Hadoop >> mail # user >> Recovering the namenode from failure

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Recovering the namenode from failure
I'm on CDH4, and trying to recover both the namenode and cloudera manager
VMs from HDFS after losing the namenode.


All of our backup VMs are on HDFS, so for the moment I just want to hack
something together, copy the backup VMs off HDFS and get on with properly
reconfiguring via CDH Manger.


So I've installed a plain 'ol namenode on one of my cluster nodes and
started it with -importCheckpoint (with the data from the secondary NN),
this seems to have worked, I have a namenode web UI up which expects to find
32178 blocks.


But my plain namenode (on the same hostname and IP as the old namenode) says
that there are no datanodes in the cluster.


What do I need in order to configure the datanodes to report their blocks
into this new namenode (same IP & hostname)?