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From "Daryn Sharp (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-4750) Support NFSv3 interface to HDFS
Date Thu, 25 Apr 2013 14:46:17 GMT

    [ https://issues.apache.org/jira/browse/HDFS-4750?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13641864#comment-13641864
] 

Daryn Sharp commented on HDFS-4750:
-----------------------------------

This part seems a bit worrisome:
bq. The solution is to close the stream after it’s idle(no write) for a certain period(e.g.,
10 seconds). The subsequent write will become append and open the stream again.

This is very semantically wrong.  If another client appended to the file in the interim, the
file position _should not_ implicitly move to the end of the file.  Assuming the proposed
approach is otherwise valid: when the client attempts to write again via append, it should
throw an exception if the file size is greater than the client's current position in the stream.
 Even that breaks POSIX semantics, but it's "less wrong" by not causing the potential for
garbled data.
                
> Support NFSv3 interface to HDFS
> -------------------------------
>
>                 Key: HDFS-4750
>                 URL: https://issues.apache.org/jira/browse/HDFS-4750
>             Project: Hadoop HDFS
>          Issue Type: New Feature
>    Affects Versions: 3.0.0
>            Reporter: Brandon Li
>            Assignee: Brandon Li
>         Attachments: HADOOP-NFS-Proposal.pdf
>
>
> Access HDFS is usually done through HDFS Client or webHDFS. Lack of seamless integration
with client’s file system makes it difficult for users and impossible for some applications
to access HDFS. NFS interface support is one way for HDFS to have such easy integration.
> This JIRA is to track the NFS protocol support for accessing HDFS. With HDFS client,
webHDFS and the NFS interface, HDFS will be easier to access and be able support more applications
and use cases. 
> We will upload the design document and the initial implementation. 

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