Help Center/ MapReduce Service/ User Guide (Kuala Lumpur Region)/ Troubleshooting/ Using HDFS/ Common File Read/Write Faults
Updated on 2022-12-14 GMT+08:00
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Common File Read/Write Faults

Symptom

When a user performs a write operation on HDFS, the message "Failed to place enough replicas:expected…" is displayed.

Cause Analysis

  • The data receiver of the DataNode is unavailable.

    The DataNode log is as follows:

    2016-03-17 18:51:44,721 | WARN | org.apache.hadoop.hdfs.server.datanode.DataXceiverServer@5386659f | hadoopc1h2:25009:DataXceiverServer: | DataXceiverServer.java:158
java.io.IOException: Xceiver count 4097 exceeds the limit of concurrent xcievers: 4096
at org.apache.hadoop.hdfs.server.datanode.DataXceiverServer.run(DataXceiverServer.java:140)
at java.lang.Thread.run(Thread.java:745)
  • The disk space configured for the DataNode is insufficient.
  • DataNode heartbeats are delayed.

Solution

  • If the DataNode data receiver is unavailable, add the value of the HDFS parameter dfs.datanode.max.transfer.threads on Manager.
  • If disk space or CPU resources are insufficient, add DataNodes or ensure that disk space and CPU resources are available.
  • If the network is faulty, ensure that the network is available.
Parent topic: Using HDFS