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This article mainly introduces the use of DataNode, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor take you to understand it.

The function of DataNode

The first is the management of local data blocks, and then the interaction with other entities, such as clients, NameNode, and other DataNode.

Second, and NameNode heartbeat.

The datanode sends a heartbeat to the namenode in a fixed period of time, and if the namenode does not receive the heartbeat for a period of time, the datanode is marked as down. The formula for calculating this period of time:

Timeout=2*heartbeat.recheck.interval+10*dfs.heartbeat.interval

The heartbeat.recheck.interval size defaults to 5 minutes.

Dfs.heartbeat.interval defaults to 30 seconds, so if namenode does not receive a message from datanode within 10 minutes and 30 seconds, it is considered to be dead.

Note: in the configuration of hdfs-site.xml, the unit of heartbeat.recheck.interval is millisecond, and the unit of dfs.heartbeat.interval is better.

The management of data blocks in DataNode, writing is a streaming structure.

Thank you for reading this article carefully. I hope the article "what's the use of DataNode" shared by the editor will be helpful to everyone? at the same time, I also hope that you will support and pay attention to the industry information channel, and more related knowledge is waiting for you to learn!

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