Some exceptions with HDFS 2.7.4

HDFS 2.7.4 is deployed in production, and some exceptions have been encountered recently, so record the memo:

一、dfs.datanode.directoryscan.throttle.limit.ms.per.sec

After the DataNode runs for a period of time, the following exception is reported:

ERROR org.apache.hadoop.hdfs.server.datanode.DirectoryScanner: dfs.datanode.directoryscan.throttle.limit.ms.per.sec set to value below 1 ms/sec. Assuming default value of 1000

Googled it and found it to be a bug:

https://issues.apache.org/jira/browse/HDFS-9274

solution:

Edit hdfs-site.xml and add the following configuration

<property>
  <name>dfs.datanode.directoryscan.throttle.limit.ms.per.sec</name>
  <value>1000</value>
</property>

After restarting HDFS, the problem is solved.

二、DataXceiver error processing WRITE_BLOCK operation

After the DataNode runs for a period of time, the following exception is reported:

ERROR org.apache.hadoop.hdfs.server.datanode.DataNode: xxxxxx:50010:DataXceiver error processing WRITE_BLOCK operation  src: /aaaaaa:58294 dst: /bbbbbb:50010

Googled it and found that the number of data transmission threads needs to be modified.

solution:

Edit hdfs-site.xml and add the following configuration

<property>
  <name>dfs.datanode.max.transfer.threads</name>
  <value>8192</value>
</property>

After restarting HDFS, the problem is solved.