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https://issues.apache.org/jira/browse/HDFS-9106?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15080549#comment-15080549
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Junping Du commented on HDFS-9106:
----------------------------------

Hi [~hitliuyi], [~jingzhao] and [~kihwal], do we think this bug should be fixed 
in branch-2.6 also?

> Transfer failure during pipeline recovery causes permanent write failures
> -------------------------------------------------------------------------
>
>                 Key: HDFS-9106
>                 URL: https://issues.apache.org/jira/browse/HDFS-9106
>             Project: Hadoop HDFS
>          Issue Type: Bug
>            Reporter: Kihwal Lee
>            Assignee: Kihwal Lee
>            Priority: Critical
>             Fix For: 2.7.2
>
>         Attachments: HDFS-9106-poc.patch, HDFS-9106.branch-2.7.patch, 
> HDFS-9106.patch
>
>
> When a new node is added to a write pipeline during flush/sync, if the 
> partial block transfer fails, the write will fail permanently without 
> retrying or continuing with whatever is in the pipeline. 
> The transfer often fails in busy clusters due to timeout. There is no 
> per-packet ACK between client and datanode or between source and target 
> datanodes. If the total transfer time exceeds the configured timeout + 10 
> seconds (2 * 5 seconds slack), it is considered failed.  Naturally, the 
> failure rate is higher with bigger block sizes.
> I propose following changes:
> - Transfer timeout needs to be different from per-packet timeout.
> - transfer should be retried if fails.



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