[jira] Updated: (HADOOP-4132) high rate of task failures because of bad of full datanodes

["Christian Kunz (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HADOOP-4132?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Christian Kunz updated HADOOP-4132:
-----------------------------------

    Priority: Blocker  (was: Major)
     Summary: high rate of task failures because of bad of full datanodes  (was: high rate of task failures because of bad datanodes)

The problem does not only occur with bad datanodes but also with full datanodes.

During a long running job the distribution of blocks written to dfs is not uniform. With 35% dfs full, 5% of datanodes are already completely full, typically having double the number of blocks compared to average.

I would have assumed that when writing to dfs, datanodes on the same rack with more space are preferred over datanodes with less space. Am I wrong?

> high rate of task failures because of bad of full datanodes
> -----------------------------------------------------------
>
>                 Key: HADOOP-4132
>                 URL: https://issues.apache.org/jira/browse/HADOOP-4132
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: dfs
>    Affects Versions: 0.17.1
>            Reporter: Christian Kunz
>            Priority: Blocker
>
> With 0.17 we notice a fast rate of task failures because of the same bad data nodes being reported repeatedly as badFirstLink. We never saw this in 0.16.
> After running less than 20,000 map tasks, more than 2,500 of them reported a single certain datanode as badFirstLink, with typical exception of the form:
> 08/09/09 14:41:14 INFO dfs.DFSClient: Exception in createBlockOutputStream java.net.SocketTimeoutException: 189000 millis timeout while waiting for channel to be ready for read. ch : java.nio.channels.SocketChannel[connected local=/xxx.yyy.zzz.ttt:38788 remote=/xxx.yyy.zzz.ttt:50010]
> 08/09/09 14:41:14 INFO dfs.DFSClient: Abandoning block blk_-3650954811734254315
> 08/09/09 14:41:14 INFO dfs.DFSClient: Waiting to find target node: xxx.yyy.zzz.ttt:50010
> 08/09/09 14:44:29 INFO dfs.DFSClient: Exception in createBlockOutputStream java.net.SocketTimeoutException: 189000 millis timeout while waiting for channel to be ready for read. ch : java.nio.channels.SocketChannel[connected local=/xxx.yyy.zzz.ttt:39014 remote=/xxx.yyy.zzz.ttt:50010]
> 08/09/09 14:44:29 INFO dfs.DFSClient: Abandoning block blk_8665387817606483066
> 08/09/09 14:44:29 INFO dfs.DFSClient: Waiting to find target node: xxx.yyy.zzz.ttt:50010
> 08/09/09 14:47:35 INFO dfs.DFSClient: Exception in createBlockOutputStream java.io.IOException: Bad connect ack with firstBadLink ip.bad.data.node:50010
> 08/09/09 14:47:35 INFO dfs.DFSClient: Abandoning block blk_8475261758012143524
> 08/09/09 14:47:35 INFO dfs.DFSClient: Waiting to find target node: xxx.yyy.zzz.ttt:50010
> 08/09/09 14:50:42 INFO dfs.DFSClient: Exception in createBlockOutputStream java.io.IOException: Bad connect ack with firstBadLink ip.bad.data.node:50010
> 08/09/09 14:50:42 INFO dfs.DFSClient: Abandoning block blk_4847638219960634858
> 08/09/09 14:50:42 INFO dfs.DFSClient: Waiting to find target node: xxx.yyy.zzz.ttt:50010
> 08/09/09 14:50:48 WARN dfs.DFSClient: DataStreamer Exception: java.io.IOException: Unable to create new block.
> 08/09/09 14:50:48 WARN dfs.DFSClient: Error Recovery for block blk_4847638219960634858 bad datanode[2]
> Exception in thread "main" java.io.IOException: Could not get block locations. Aborting...
> With several such bad datanodes the probability of jobs failing goes up a lot.

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