Shulou(Shulou.com)06/01 Report--

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

A DataNode is a software node that runs on a separate machine in a HDFS instance; usually a Hadoop cluster consists of a NameNode and a large number of DataNode,DataNode are usually organized in a rack, all racks connect all systems through a single switch.

This article operating environment: Windows10 system, nodejs version 12.19.0, Dell G3 computer.

What does datanode mean?

DataNode is a software node that runs on a separate machine in a HDFS instance. Usually a Hadoop cluster consists of a NameNode and a large number of DataNode. DataNode is usually organized as a rack, and all racks connect all systems through a single switch.

DataNode responds to read and write requests from HDFS clients as well as commands from NameNode to create, delete, and copy blocks. NameNode relies on periodic heartbeat (heartbeat) messages from each DataNode. Each message contains a block report against which NameNode can validate block mappings and other file system metadata. If DataNode cannot send a heartbeat message, NameNode will take remedial action. Re-copy the block lost on this node.

Datenode provides storage services for real file data.

Block: the most basic unit of storage. For the content of a file, the length and size of a file size, then starting from the zero offset of the file, the file is divided and numbered according to the fixed size and order, and each divided is called a Block. The default BIock size for HDFS is 128MB.

Unlike ordinary file systems, in HDFS, if a file is less than the size of a data block, it does not occupy the entire data storage space.

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

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.