Distcp Between kerberized and none-kerberized Cluster

The standard tool for copying data between two clusters is probably distcp. It can also be used to keep the data of two clusters updated. Here the update process is a asynchronous process using a fairly basic update strategy. Distcp is a simple tool, but some edge cases can get complicated. For once the distributed copy between two HA clusters is such a case. Also important to know is that since the versions of RPC used by HDFS can be different it is always a good idea to use a read only protocol like hftp or webhdfs to copy the data from the source system. So the URL could look like this hftp://source.cluster/users/me . WebHDFS would also work, because it is not using RPC.

Another corner case using distcp is the need to copy data between a secure and none secure cluster. Such a process should always be triggered from the secure cluster. This would be the cluster the owner of the cluster has a valid ticket to authenticate against the secure cluster. But this would still yield an exception as the system would complain about a missing fallback mechanism. On the secure cluster it is important to set the  ipc.client.fallback-to-simple-auth-allowed to true in the core-site.xml  in order to make this work.

<property>
  <name>ipc.client.fallback-to-simple-auth-allowed</name>
  <value>true</value>
</property>

What is left to to is make sure the user has the needed right on both systems to read and write the data.

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