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https://issues.apache.org/jira/browse/HDFS-9106?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15019098#comment-15019098
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Sangjin Lee commented on HDFS-9106:
-----------------------------------
Does this issue exist in 2.6.x? Should this be backported to branch-2.6?
> 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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