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From Marcos Ortiz <mlor...@uci.cu>
Subject Re: Could not obtain block
Date Wed, 09 Mar 2011 15:31:48 GMT
El 3/9/2011 6:27 AM, Evert Lammerts escribió:
> We see a lot of IOExceptions coming from HDFS during a job that does nothing but untar
100 files (1 per Mapper, sizes vary between 5GB and 80GB) that are in HDFS, to HDFS. DataNodes
are also showing Exceptions that I think are related. (See stacktraces below.)
>
> This job should not be able to overload the system I think... I realize that much data
needs to go over the lines, but HDFS should still be responsive. Any ideas / help is much
appreciated!
>
> Some details:
> * Hadoop 0.20.2 (CDH3b4)
> * 5 node cluster plus 1 node for JT/NN (Sun Thumpers)
> * 4 cores/node, 4GB RAM/core
> * CentOS 5.5
>
> Job output:
>
> java.io.IOException: java.io.IOException: Could not obtain block: blk_-3695352030358969086_130839
file=/user/emeij/icwsm-data-test/01-26-SOCIAL_MEDIA.tar.gz
>    
Which is the ouput of:
   bin/hadoop dfsadmin -report

Which is the output of:
   bin/hadoop fsck /user/emeij/icwsm-data-test/
> 	at ilps.DownloadICWSM$UntarMapper.map(DownloadICWSM.java:449)
> 	at ilps.DownloadICWSM$UntarMapper.map(DownloadICWSM.java:1)
> 	at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50)
> 	at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:390)
> 	at org.apache.hadoop.mapred.MapTask.run(MapTask.java:324)
> 	at org.apache.hadoop.mapred.Child$4.run(Child.java:240)
> 	at java.security.AccessController.doPrivileged(Native Method)
> 	at javax.security.auth.Subject.doAs(Subject.java:396)
> 	at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1115)
> 	at org.apache.hadoop.mapred.Child.main(Child.java:234)
> Caused by: java.io.IOException: Could not obtain block: blk_-3695352030358969086_130839
file=/user/emeij/icwsm-data-test/01-26-SOCIAL_MEDIA.tar.gz
>    
Which is the ouput of:
  bin/hadoop fsck /user/emeij/icwsm-data-test/01-26-SOCIAL_MEDIA.tar.gz 
--files -blocks -racks
> 	at org.apache.hadoop.hdfs.DFSClient$DFSInputStream.chooseDataNode(DFSClient.java:1977)
> 	at org.apache.hadoop.hdfs.DFSClient$DFSInputStream.blockSeekTo(DFSClient.java:1784)
> 	at org.apache.hadoop.hdfs.DFSClient$DFSInputStream.read(DFSClient.java:1932)
> 	at java.io.DataInputStream.read(DataInputStream.java:83)
> 	at org.apache.hadoop.io.IOUtils.copyBytes(IOUtils.java:55)
> 	at org.apache.hadoop.io.IOUtils.copyBytes(IOUtils.java:74)
> 	at org.apache.hadoop.fs.FileUtil.copy(FileUtil.java:335)
> 	at ilps.DownloadICWSM$CopyThread.run(DownloadICWSM.java:149)
>
>
> Example DataNode Exceptions (not that these come from the node at 192.168.28.211):
>
> 2011-03-08 19:40:40,297 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Exception
in receiveBlock for block blk_-9222067946733189014_3798233 java.io.EOFException: while trying
to read 3067064 bytes
> 2011-03-08 19:40:41,018 INFO org.apache.hadoop.hdfs.server.datanode.DataNode.clienttrace:
src: /192.168.28.211:50050, dest: /192.168.28.211:49748, bytes: 0, op: HDFS_READ, cliID: DFSClient_attempt_201103071120_0030_m_000032_0,
offset: 30
> 72, srvID: DS-568746059-145.100.2.180-50050-1291128670510, blockid: blk_3596618013242149887_4060598,
duration: 2632000
> 2011-03-08 19:40:41,049 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Exception
in receiveBlock for block blk_-9221028436071074510_2325937 java.io.EOFException: while trying
to read 2206400 bytes
> 2011-03-08 19:40:41,348 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Exception
in receiveBlock for block blk_-9221549395563181322_4024529 java.io.EOFException: while trying
to read 3037288 bytes
> 2011-03-08 19:40:41,357 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Exception
in receiveBlock for block blk_-9221885906633018147_3895876 java.io.EOFException: while trying
to read 1981952 bytes
> 2011-03-08 19:40:41,434 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Block blk_-9221885906633018147_3895876
unfinalized and removed.
> 2011-03-08 19:40:41,434 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: writeBlock
blk_-9221885906633018147_3895876 received exception java.io.EOFException: while trying to
read 1981952 bytes
> 2011-03-08 19:40:41,434 ERROR org.apache.hadoop.hdfs.server.datanode.DataNode: DatanodeRegistration(192.168.28.211:50050,
storageID=DS-568746059-145.100.2.180-50050-1291128670510, infoPort=50075, ipcPort=50020):DataXceiver
> java.io.EOFException: while trying to read 1981952 bytes
>          at org.apache.hadoop.hdfs.server.datanode.BlockReceiver.readToBuf(BlockReceiver.java:270)
>          at org.apache.hadoop.hdfs.server.datanode.BlockReceiver.readNextPacket(BlockReceiver.java:357)
>          at org.apache.hadoop.hdfs.server.datanode.BlockReceiver.receivePacket(BlockReceiver.java:378)
>          at org.apache.hadoop.hdfs.server.datanode.BlockReceiver.receiveBlock(BlockReceiver.java:534)
>          at org.apache.hadoop.hdfs.server.datanode.DataXceiver.writeBlock(DataXceiver.java:417)
>          at org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:122)
> 2011-03-08 19:40:41,465 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Block blk_-9221549395563181322_4024529
unfinalized and removed.
> 2011-03-08 19:40:41,466 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: writeBlock
blk_-9221549395563181322_4024529 received exception java.io.EOFException: while trying to
read 3037288 bytes
> 2011-03-08 19:40:41,466 ERROR org.apache.hadoop.hdfs.server.datanode.DataNode: DatanodeRegistration(192.168.28.211:50050,
storageID=DS-568746059-145.100.2.180-50050-1291128670510, infoPort=50075, ipcPort=50020):DataXceiver
> java.io.EOFException: while trying to read 3037288 bytes
>          at org.apache.hadoop.hdfs.server.datanode.BlockReceiver.readToBuf(BlockReceiver.java:270)
>          at org.apache.hadoop.hdfs.server.datanode.BlockReceiver.readNextPacket(BlockReceiver.java:357)
>          at org.apache.hadoop.hdfs.server.datanode.BlockReceiver.receivePacket(BlockReceiver.java:378)
>          at org.apache.hadoop.hdfs.server.datanode.BlockReceiver.receiveBlock(BlockReceiver.java:534)
>          at org.apache.hadoop.hdfs.server.datanode.DataXceiver.writeBlock(DataXceiver.java:417)
>          at org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:122)
>
> Cheers,
>
> Evert Lammerts
> Consultant eScience&  Cloud Services
> SARA Computing&  Network Services
> Operations, Support&  Development
>
> Phone: +31 20 888 4101
> Email: evert.lammerts@sara.nl
> http://www.sara.nl
>
>
>    

Then on the DataNode where you have the particular block 
(blk_-3695352030358969086_130839 )
you can visit the web interface 
http://192.168.28.211:50075/blockScannerReport to see what's happening 
on the node

Regards

-- 
Marcos Luís Ortíz Valmaseda
  Software Engineer
  Universidad de las Ciencias Informáticas
  Linux User # 418229

http://uncubanitolinuxero.blogspot.com
http://www.linkedin.com/in/marcosluis2186


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