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https://issues.apache.org/jira/browse/HDFS-101?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12782669#action_12782669
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Hairong Kuang commented on HDFS-101:
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It seems to me there are two issues with this problem:
1. If a datanode gets an error receiving a block, it should not simply stop
itself. Instead, it should send a failure ack back.
2. The datanode should also identify the source of the error, whether it is
caused by itself or the other datanodes in the pipeline, and then report the
correct information back.
> DFS write pipeline : DFSClient sometimes does not detect second datanode
> failure
> ---------------------------------------------------------------------------------
>
> Key: HDFS-101
> URL: https://issues.apache.org/jira/browse/HDFS-101
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Raghu Angadi
> Assignee: Hairong Kuang
> Priority: Blocker
> Fix For: 0.21.0
>
>
> When the first datanode's write to second datanode fails or times out
> DFSClient ends up marking first datanode as the bad one and removes it from
> the pipeline. Similar problem exists on DataNode as well and it is fixed in
> HADOOP-3339. From HADOOP-3339 :
> "The main issue is that BlockReceiver thread (and DataStreamer in the case of
> DFSClient) interrupt() the 'responder' thread. But interrupting is a pretty
> coarse control. We don't know what state the responder is in and interrupting
> has different effects depending on responder state. To fix this properly we
> need to redesign how we handle these interactions."
> When the first datanode closes its socket from DFSClient, DFSClient should
> properly read all the data left in the socket.. Also, DataNode's closing of
> the socket should not result in a TCP reset, otherwise I think DFSClient will
> not be able to read from the socket.
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