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Posted to common-dev@hadoop.apache.org by "Raghu Angadi (JIRA)" <ji...@apache.org> on 2009/05/13 09:16:45 UTC
[jira] Issue Comment Edited: (HADOOP-5713) File write fails after
data node goes down
[ https://issues.apache.org/jira/browse/HADOOP-5713?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12708804#action_12708804 ]
Raghu Angadi edited comment on HADOOP-5713 at 5/13/09 12:15 AM:
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oh.. right. I read it incorrectly. In DFSClient errors during initial connect seem to be treated differently from errors during rest of the writing of the block.. In that sense temp exclude list should work for the connect problem on large clusters.
But somehow client telling NN what to allocate is less appealing to me. Is it better to treat both errors similarly.. ie client could continue just with remaining good nodes?
was (Author: rangadi):
oh.. right. errors during initial connect seem to be treated differently from errors during rest of the writing of the block.. In that sense temp exclude list should work for the connect problem on large clusters.
But somehow client telling NN what to allocate is less appealing to me. Is it better to treat both errors similarly.. ie client could continue just with remaining good nodes?
> File write fails after data node goes down
> ------------------------------------------
>
> Key: HADOOP-5713
> URL: https://issues.apache.org/jira/browse/HADOOP-5713
> Project: Hadoop Core
> Issue Type: Bug
> Components: dfs
> Reporter: Alban Chevignard
> Attachments: failed_write.patch
>
>
> If a data node goes down while a file is being written do HDFS, the write fails with the following errors:
> {noformat}
> 09/04/20 17:15:39 INFO dfs.DFSClient: Exception in createBlockOutputStream java.io.IOException:
> Bad connect ack with firstBadLink 192.168.0.66:50010
> 09/04/20 17:15:39 INFO dfs.DFSClient: Abandoning block blk_-6792221430152215651_1003
> 09/04/20 17:15:45 INFO dfs.DFSClient: Exception in createBlockOutputStream java.io.IOException:
> Bad connect ack with firstBadLink 192.168.0.66:50010
> 09/04/20 17:15:45 INFO dfs.DFSClient: Abandoning block blk_-1056044503329698571_1003
> 09/04/20 17:15:51 INFO dfs.DFSClient: Exception in createBlockOutputStream java.io.IOException:
> Bad connect ack with firstBadLink 192.168.0.66:50010
> 09/04/20 17:15:51 INFO dfs.DFSClient: Abandoning block blk_-1144491637577072681_1003
> 09/04/20 17:15:57 INFO dfs.DFSClient: Exception in createBlockOutputStream java.io.IOException:
> Bad connect ack with firstBadLink 192.168.0.66:50010
> 09/04/20 17:15:57 INFO dfs.DFSClient: Abandoning block blk_6574618270268421892_1003
> 09/04/20 17:16:03 WARN dfs.DFSClient: DataStreamer Exception: java.io.IOException:
> Unable to create new block.
> at org.apache.hadoop.dfs.DFSClient$DFSOutputStream.nextBlockOutputStream(DFSClient.java:2387)
> at org.apache.hadoop.dfs.DFSClient$DFSOutputStream.access$1800(DFSClient.java:1746)
> at org.apache.hadoop.dfs.DFSClient$DFSOutputStream$DataStreamer.run(DFSClient.java:1924)
> 09/04/20 17:16:03 WARN dfs.DFSClient: Error Recovery for block blk_6574618270268421892_1003 bad datanode[1]
> {noformat}
> The tests were done with the following configuration:
> * Hadoop version 0.18.3
> * 3 data nodes with replication count of 2
> * 1 GB file write
> * 1 data node taken down during write
> This issue seems to be caused by the fact that there is a delay between the time a data node goes down and the time it is marked as dead by the name node. This delay is unavoidable, but the name node should not keep allocating new blocks to data nodes that are known to be down by the client. Even by adjusting {{heartbeat.recheck.interval}}, there is still a window during which this issue can occur.
> One possible fix would be to allow clients to exclude known bad data nodes when allocating new blocks. See {{failed_write.patch}} for an example.
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