[HDFS-3179] Improve the error message: DataStreamer throw an exception, "nodes.length != original.length + 1" on single datanode cluster

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.23.2
• Fix Version/s: 2.0.0-alpha
• Component/s: hdfs-client
• Hadoop Flags: Reviewed
• Assignee: Tsz-wo Sze
• Reporter: Zhanwei Wang
• Created: 02/Apr/12 20:53
• Updated: 28/Sep/15 20:58
• Resolved: 11/Apr/12 17:53

Description

Create a single datanode cluster

disable permissions
enable webhfds
start hdfs
run the test script

expected result:
a file named "test" is created and the content is "testtest"

the result I got:
hdfs throw an exception on the second append operation.

./test.sh 
{"RemoteException":{"exception":"IOException","javaClassName":"java.io.IOException","message":"Failed to add a datanode: nodes.length != original.length + 1, nodes=[127.0.0.1:50010], original=[127.0.0.1:50010]"}}

Log in datanode:

2012-04-02 14:34:21,058 WARN org.apache.hadoop.hdfs.DFSClient: DataStreamer Exception
java.io.IOException: Failed to add a datanode: nodes.length != original.length + 1, nodes=[127.0.0.1:50010], original=[127.0.0.1:50010]
	at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.findNewDatanode(DFSOutputStream.java:778)
	at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.addDatanode2ExistingPipeline(DFSOutputStream.java:834)
	at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.setupPipelineForAppendOrRecovery(DFSOutputStream.java:930)
	at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.run(DFSOutputStream.java:461)
2012-04-02 14:34:21,059 ERROR org.apache.hadoop.hdfs.DFSClient: Failed to close file /test
java.io.IOException: Failed to add a datanode: nodes.length != original.length + 1, nodes=[127.0.0.1:50010], original=[127.0.0.1:50010]
	at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.findNewDatanode(DFSOutputStream.java:778)
	at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.addDatanode2ExistingPipeline(DFSOutputStream.java:834)
	at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.setupPipelineForAppendOrRecovery(DFSOutputStream.java:930)
	at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.run(DFSOutputStream.java:461)

test.sh

#!/bin/sh

echo "test" > test.txt

curl -L -X PUT "http://localhost:50070/webhdfs/v1/test?op=CREATE"

curl -L -X POST -T test.txt "http://localhost:50070/webhdfs/v1/test?op=APPEND"
curl -L -X POST -T test.txt "http://localhost:50070/webhdfs/v1/test?op=APPEND"