hadoop跑任务搞的好好的，后来把hadoop-dir移了一个位置，结果报错：

java.io.EOFException: Premature EOF: no length prefix available
        at org.apache.hadoop.hdfs.protocolPB.PBHelper.vintPrefixed(PBHelper.java:1492)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.createBlockOutputStream(DFSOutputStream.java:1155)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.nextBlockOutputStream(DFSOutputStream.java:1088)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.run(DFSOutputStream.java:514)
15/03/24 18:26:40 INFO hdfs.DFSClient: Abandoning BP-1909118226-192.168.19.234-1427110524238:blk_1073762363_21550
15/03/24 18:26:40 INFO hdfs.DFSClient: Excluding datanode 192.168.21.24:50010
copy from: /root/zenggq/jn2/data2w/t0.head_2000 to /recom1000/t0.head_2000
15/03/24 18:26:41 INFO hdfs.DFSClient: Exception in createBlockOutputStream
java.io.EOFException: Premature EOF: no length prefix available
        at org.apache.hadoop.hdfs.protocolPB.PBHelper.vintPrefixed(PBHelper.java:1492)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.createBlockOutputStream(DFSOutputStream.java:1155)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.nextBlockOutputStream(DFSOutputStream.java:1088)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.run(DFSOutputStream.java:514)
15/03/24 18:26:41 INFO hdfs.DFSClient: Abandoning BP-1909118226-192.168.19.234-1427110524238:blk_1073762365_21552
15/03/24 18:26:41 INFO hdfs.DFSClient: Excluding datanode 192.168.21.23:50010
15/03/24 18:26:41 INFO hdfs.DFSClient: Exception in createBlockOutputStream
java.io.IOException: Bad connect ack with firstBadLink as 192.168.21.24:50010
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.createBlockOutputStream(DFSOutputStream.java:1166)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.nextBlockOutputStream(DFSOutputStream.java:1088)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.run(DFSOutputStream.java:514)
15/03/24 18:26:41 INFO hdfs.DFSClient: Abandoning BP-1909118226-192.168.19.234-1427110524238:blk_1073762366_21553
15/03/24 18:26:41 INFO hdfs.DFSClient: Excluding datanode 192.168.21.24:50010
15/03/24 18:26:41 INFO hdfs.DFSClient: Exception in createBlockOutputStream
java.io.EOFException: Premature EOF: no length prefix available
        at org.apache.hadoop.hdfs.protocolPB.PBHelper.vintPrefixed(PBHelper.java:1492)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.createBlockOutputStream(DFSOutputStream.java:1155)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.nextBlockOutputStream(DFSOutputStream.java:1088)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.run(DFSOutputStream.java:514)
15/03/24 18:26:41 INFO hdfs.DFSClient: Abandoning BP-1909118226-192.168.19.234-1427110524238:blk_1073762367_21554
15/03/24 18:26:41 INFO hdfs.DFSClient: Excluding datanode 192.168.19.236:50010
15/03/24 18:26:41 INFO hdfs.DFSClient: Exception in createBlockOutputStream
java.io.EOFException: Premature EOF: no length prefix available
        at org.apache.hadoop.hdfs.protocolPB.PBHelper.vintPrefixed(PBHelper.java:1492)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.createBlockOutputStream(DFSOutputStream.java:1155)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.nextBlockOutputStream(DFSOutputStream.java:1088)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.run(DFSOutputStream.java:514)
15/03/24 18:26:41 INFO hdfs.DFSClient: Abandoning BP-1909118226-192.168.19.234-1427110524238:blk_1073762368_21555
15/03/24 18:26:41 INFO hdfs.DFSClient: Excluding datanode 192.168.21.30:50010
15/03/24 18:26:41 WARN hdfs.DFSClient: DataStreamer Exception
java.io.IOException: Unable to create new block.
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.nextBlockOutputStream(DFSOutputStream.java:1100)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.run(DFSOutputStream.java:514)
15/03/24 18:26:41 WARN hdfs.DFSClient: Could not get block locations. Source file "/recom1000/t1.head_2000" - Aborting...
Exception in thread "main" java.io.EOFException: Premature EOF: no length prefix available
        at org.apache.hadoop.hdfs.protocolPB.PBHelper.vintPrefixed(PBHelper.java:1492)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.createBlockOutputStream(DFSOutputStream.java:1155)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.nextBlockOutputStream(DFSOutputStream.java:1088)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.run(DFSOutputStream.java:514)
15/03/24 18:26:41 ERROR hdfs.DFSClient: Failed to close file /recom1000/t1.head_2000
java.io.EOFException: Premature EOF: no length prefix available
        at org.apache.hadoop.hdfs.protocolPB.PBHelper.vintPrefixed(PBHelper.java:1492)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.createBlockOutputStream(DFSOutputStream.java:1155)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.nextBlockOutputStream(DFSOutputStream.java:1088)
        at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.run(DFSOutputStream.java:514)
[root@master jn2]#

找了一圈答案没有，一说是datanode进程没有，而说是防火墙没关。结果我这两个都没问题。

后来我把hadoop-dir下的data目录删了。然后重新格式化namenode

hadoop namenode -format

然后的然后就是好了