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From "Jing Zhao (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-5563) NFS gateway should commit the buffered data when read request comes after write to the same file
Date Wed, 27 Nov 2013 23:18:36 GMT

    [ https://issues.apache.org/jira/browse/HDFS-5563?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13834311#comment-13834311
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Jing Zhao commented on HDFS-5563:
---------------------------------

bq. In the future, we can consider use fix-sized cache blocks so that it's easy to find the
cached data for read.

Sounds good. +1 pending Jenkins.

> NFS gateway should commit the buffered data when read request comes after write to the
same file
> ------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-5563
>                 URL: https://issues.apache.org/jira/browse/HDFS-5563
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: nfs
>            Reporter: Brandon Li
>            Assignee: Brandon Li
>         Attachments: HDFS-5563.001.patch, HDFS-5563.002.patch, HDFS-5563.003.patch
>
>
> HDFS write is asynchronous and data may not be available to read immediately after write.
> One of the main reason is that DFSClient doesn't flush data to DN until its local buffer
is full.
> To workaround this problem, when a read comes after write to the same file, NFS gateway
should sync the data so the read request can get the latest content. The drawback is that,
the frequent hsync() call can slow down data write.



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