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From "Jinghui Wang (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HDFS-5280) Corrupted meta files on data nodes prevents DFClient from connecting to data nodes and updating corruption status to name node.
Date Mon, 30 Sep 2013 21:24:25 GMT
Jinghui Wang created HDFS-5280:
----------------------------------

             Summary: Corrupted meta files on data nodes prevents DFClient from connecting
to data nodes and updating corruption status to name node.
                 Key: HDFS-5280
                 URL: https://issues.apache.org/jira/browse/HDFS-5280
             Project: Hadoop HDFS
          Issue Type: Bug
          Components: datanode, hdfs-client
    Affects Versions: 2.0.4-alpha, 2.1.0-beta, 1.1.1
         Environment: Red hat enterprise 6.4
Hadoop-2.1.0
            Reporter: Jinghui Wang


Meta files being corrupted causes the DFSClient not able to connect to the datanodes to access
the blocks, so DFSClient never perform a read on the block, which is what throws the ChecksumException
when file blocks are corrupted and report to the namenode to mark the block as corrupt.  Since
the client never got to that far, thus the file status remain as healthy and so are all the
blocks.

To replicate the error, put a file onto HDFS.
run hadoop fsck /tmp/bogus.csv -files -blocks -location will get that following output.
FSCK started for path /tmp/bogus.csv at 11:33:29
/tmp/bogus.csv 109 bytes, 1 block(s):  OK
0. blk_-4255166695856420554_5292 len=109 repl=3

find the block/meta files for 4255166695856420554 by running 
ssh datanode1.address find /hadoop/ -name "*4255166695856420554*" and it will get the following
output:
/hadoop/data1/hdfs/current/subdir2/blk_-4255166695856420554
/hadoop/data1/hdfs/current/subdir2/blk_-4255166695856420554_5292.meta

now corrupt the meta file by running 
ssh datanode1.address "sed -i -e '1i 1234567891' /hadoop/data1/hdfs/current/subdir2/blk_-4255166695856420554_5292.meta"


now run hadoop fs -cat /tmp/bogus.csv
will show the stack trace of DFSClient failing to connect to the data node with the corrupted
meta file.



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