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https://issues.apache.org/jira/browse/HDFS-9868?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15882089#comment-15882089
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Yongjun Zhang commented on HDFS-9868:
-------------------------------------

Thanks for the new rev that implements confMap [~xiaochen], below are my 
comments:

# separate the /log4j.properties change to a new jira
# loading confMap file should be done once at initialization, and then the map 
is used when needed. Currently it's open one time for each file, which should 
really be avoided, especially for many-file cases, this would certainly impact 
performance.
# should not create a conf object for each file, it should be a ref to a common 
conf object created in item 2 above.
# FileSystemAccessService has a better implementation of loading conf file.
# suggest to add a method in Path class to get back the cluster path, instead 
of creating it at client code.

Would you please address these and I will review further after that.

Thanks.


> Add ability for DistCp to run between 2 clusters
> ------------------------------------------------
>
>                 Key: HDFS-9868
>                 URL: https://issues.apache.org/jira/browse/HDFS-9868
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: distcp
>    Affects Versions: 2.7.1
>            Reporter: NING DING
>            Assignee: NING DING
>         Attachments: HDFS-9868.05.patch, HDFS-9868.06.patch, 
> HDFS-9868.07.patch, HDFS-9868.08.patch, HDFS-9868.1.patch, HDFS-9868.2.patch, 
> HDFS-9868.3.patch, HDFS-9868.4.patch
>
>
> Normally the HDFS cluster is HA enabled. It could take a long time when 
> coping huge data by distp. If the source cluster changes active namenode, the 
> distp will run failed. This patch supports the DistCp can read source cluster 
> files in HA access mode. A source cluster configuration file needs to be 
> specified (via the -sourceClusterConf option).
>   The following is an example of the contents of a source cluster 
> configuration
>   file:
> {code:xml}
>     <configuration>
>       <property>
>               <name>fs.defaultFS</name>
>               <value>hdfs://mycluster</value>
>         </property>
>         <property>
>               <name>dfs.nameservices</name>
>               <value>mycluster</value>
>         </property>
>         <property>
>               <name>dfs.ha.namenodes.mycluster</name>
>               <value>nn1,nn2</value>
>         </property>
>         <property>
>               <name>dfs.namenode.rpc-address.mycluster.nn1</name>
>               <value>host1:9000</value>
>         </property>
>         <property>
>               <name>dfs.namenode.rpc-address.mycluster.nn2</name>
>               <value>host2:9000</value>
>         </property>
>         <property>
>               <name>dfs.namenode.http-address.mycluster.nn1</name>
>               <value>host1:50070</value>
>         </property>
>         <property>
>               <name>dfs.namenode.http-address.mycluster.nn2</name>
>               <value>host2:50070</value>
>         </property>
>         <property>
>               <name>dfs.client.failover.proxy.provider.mycluster</name>
>               
> <value>org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider</value>
>         </property>
>       </configuration>
> {code}
>   The invocation of DistCp is as below:
> {code}
>     bash$ hadoop distcp -sourceClusterConf sourceCluster.xml /foo/bar 
> hdfs://nn2:8020/bar/foo
> {code}



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