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https://issues.apache.org/jira/browse/HDFS-7270?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14211668#comment-14211668
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Haohui Mai commented on HDFS-7270:
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The v1 patch introduces a mechanism so that a DN can flag itself as congested.
There is no policy implemented in this patch.
The implementation is based on the idea proposed in RFC 3168. It takes the 6th
and the 7th bits on the pipeline ack to flag the state of the congestion
information. It is wire compatible with the old versions.
> Implementing congestion control in writing pipeline
> ---------------------------------------------------
>
> Key: HDFS-7270
> URL: https://issues.apache.org/jira/browse/HDFS-7270
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: datanode
> Reporter: Haohui Mai
> Assignee: Haohui Mai
> Attachments: HDFS-7270.000.patch
>
>
> When a client writes to HDFS faster than the disk bandwidth of the DNs, it
> saturates the disk bandwidth and put the DNs unresponsive. The client only
> backs off by aborting / recovering the pipeline, which leads to failed writes
> and unnecessary pipeline recovery.
> This jira proposes to add explicit congestion control mechanisms in the
> writing pipeline.
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