HDFS write process.What to do if an error occurs on a DataNode during the writing process. enter image description here

CodePudding user response：

It depends on the configuration of HDFS. By default, it has a replication factor of 3, which means there must be three copies of the data at all times. If the write to one of the DataNodes fails, then the data will be in an under-replicated state.

There will be warnings in the log file about this until the problem is resolved. Since HDFS will automatically try to replicate from one of the two other DataNodes (where it was successfully written) to another DataNode, the issue should be resolved automatically if you have additional DataNodes available or replace the one that failed.