How is a file written in hdfs?

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When a file is written in hdfs, is the transfer of data done sequentially or parallelly? And how is the data replicated on other datanodes?
Dec 21, 2018 in Big Data Hadoop by slayer
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1 answer to this question.

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When you copy a file from the local file system to HDFS or when you a create a new file in HDFS, the blocks are copied sequentially. Which means that the first block is copied to a datanode first, then the second block is copied to a datanode and so on until the last block.

When the data of one datanode node is replicated to other datanodes, it is done in parallel. When a datanode receives data of the block from the client, the datanode saves the data in a file, and simultaneously replicates this data to another datanode.
answered Dec 21, 2018 by Omkar
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