Thus by parallel processing, hadoop’s distcp is the better option to copy bulk data/ huge number of files from one machine to another (or cluster to cluster) than using fs -put or fs -cp commands. But the advantage of using hadoop distcp command will give us the flexibility to specify the number of parallel tasks should be run in the background to copy files between clusters. only one process will be run to copy file by file. Hadoop fs -put command or hadoop fs -cp command can be used to copy the files from local file system into hadoop cluster and from one hadoop cluster to another respectively but here the process is sequential, i.e. In the below example, we have copied only missing files from /test to /input directory using maximum of 5 mappers.ĭirectory structures before issuing distcp and after issue are also presented.Īdvantages over hadoop fs -put command or hadoop fs -cp: delete : Deletes the existing files in the destination directory but not in source directory. m : This option lets user to specify the maximum number of mappers to be used. Iii). -update: If we need to copy only missing files or changed files, this options is very helpful and minimizes the copy time by copying only missing files/updated files instead of all the source files. overwrite: By default distcp will skip copying the files that already exist in the destination directory but these can be overwritten unconditionally with this option. Either all files are copied entirely or no file is copied. This makes sure that no partial copying is allowed. atomic:This option is used to either commit all changes at a time or no changes should be committed. All these are not mandatory but just optional. Some of the frequently useful command options are listed below. The entire source directory /sample will be copied into output directory resulting in directory structure of /example/sample. Below is the screen shot of source and destination directory structure before copying:ģ. To intelligently search through possible solutions and use reasoning to do so is a tool for AI. In this section of the Python AI Tutorial, we will study the different tools used in Artificial Intelligence: Python AI Tutorial Artificial Intelligence Tools. then hdfs://namenode can be removed from the syntax.ġ. Python AI Tutorial Artificial Intelligence Tools. In this post, parallel copying within same cluster is described. This command can be run from source machine/environment. $ hadoop distcp hdfs : //nameservice1/user/hive/warehouse/ap_us_stage.db/sales_market hdfs://nameservice2/user/aravind/sales_market
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