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https://issues.apache.org/jira/browse/HDFS-7270?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14264513#comment-14264513
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Haohui Mai commented on HDFS-7270:
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bq. Why do we need the SUPPORTED2 value?
This follows the RFC 3168. The {{SUPPORTED2}} value can be used to implement
ECN-nonce (RFC 3540) if required.
bq. Can we add test cases to ensure ECN.SUPPORTED and ECN.CONGESTED are
propagated?
I found it really difficult to expose the information in the test. If you have
an idea please let me know.
> Add congestion signaling capability to DataNode write protocol
> --------------------------------------------------------------
>
> 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, HDFS-7270.001.patch,
> HDFS-7270.002.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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