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https://issues.apache.org/jira/browse/HDFS-7661?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15227433#comment-15227433
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Mingliang Liu commented on HDFS-7661:
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Thanks for the detailed explanation, [~zhz]. I got the idea of avoiding
overwritten, which may simplify the problem.
I agree that once the stripe is full (for all parity DN) the cellBuffers for
the current stripe is useless. I'm not sure I understand your idea of managing
cellBuffer across stripes. One quick comment is that, if parity DN deletes the
cellBuffers once it finds the current stripe is full, what if the writer fails
when the full stripe has not been sent to all parity DNs? In this case, some of
the parity DN has deleted the cellBuffers so the last flushed data is not
available any more, while the other parity DNs have not received the parity
cell for the full stripe. The reader client is not able to read either last
flushed data or full stripe data in this case.
> [umbrella] support hflush and hsync for erasure coded files
> -----------------------------------------------------------
>
> Key: HDFS-7661
> URL: https://issues.apache.org/jira/browse/HDFS-7661
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: erasure-coding
> Reporter: Tsz Wo Nicholas Sze
> Assignee: GAO Rui
> Attachments: EC-file-flush-and-sync-steps-plan-2015-12-01.png,
> HDFS-7661-unitTest-wip-trunk.patch, HDFS-7661-wip.01.patch,
> HDFS-EC-file-flush-sync-design-v20160323.pdf,
> HDFS-EC-file-flush-sync-design-version1.1.pdf
>
>
> We also need to support hflush/hsync and visible length.
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