How do I copy HDFS files to another server?

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by emie , in category: General Help , 7 months ago

How do I copy HDFS files to another server?

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2 answers

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by rylan , 6 months ago

@emie 

There are multiple ways to copy HDFS files to another server. Here are a few commonly used methods:

  1. Using the hdfs dfs -get command: You can use this command to copy files or directories from HDFS to the local file system of your server. For example, to copy a file named "file1.txt" from HDFS to the local file system, you can run the following command: hdfs dfs -get /path/to/file1.txt /path/on/local/server/
  2. Using the hdfs dfs -copyToLocal command: This command is similar to the previous method, but it allows you to copy files from HDFS to the local file system using a wildcard expression. For example, to copy all files in a directory named "dir1" from HDFS to the local file system, you can run the following command: hdfs dfs -copyToLocal /path/to/dir1/* /path/on/local/server/
  3. Using the hdfs dfs -copyFromLocal command: If you have the files on your local machine and want to copy them to HDFS, you can use this command. For example, to copy a file named "file1.txt" from the local file system to HDFS, you can run the following command: hdfs dfs -copyFromLocal /path/on/local/server/file1.txt /path/in/hdfs/


Remember to replace "/path/to/" with the actual HDFS path and "/path/on/local/server/" with the actual local file system path.


Keep in mind that these commands assume that you have Hadoop installed and the necessary permissions to access the HDFS cluster.

Member

by tina , 19 days ago

@emie 

Additionally, you can also copy files from one HDFS cluster to another using DistCp. DistCp (distributed copy) is a tool used for large inter/intra-cluster copying. It is optimized for Hadoop and can copy data in parallel.


Here's how you can use DistCp to copy files from one HDFS cluster to another:

  1. Run the following DistCp command:
1
hadoop distcp hdfs://source-cluster:9000/source-path hdfs://destination-cluster:9000/destination-path


Make sure to replace source-cluster, source-path, destination-cluster, and destination-path with your actual cluster details and paths.

  1. The DistCp command will start copying the files/directories from the source HDFS cluster to the destination HDFS cluster.
  2. You can monitor the progress of the DistCp job using the MapReduce Job Tracking UI or by checking the logs.


Using DistCp is a recommended approach for large-scale copying between HDFS clusters as it provides optimizations for efficient data transfer.