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From "Brandon Li (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-4750) Support NFSv3 interface to HDFS
Date Thu, 25 Apr 2013 03:54:16 GMT

    [ https://issues.apache.org/jira/browse/HDFS-4750?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13641379#comment-13641379
] 

Brandon Li commented on HDFS-4750:
----------------------------------

Hi Brock, I was about to send you the link to this JIRA. Glad you already noticed it.
I've resolved HDFS-252 as a dup.  
I studied your NFSv4 implementation and learned a lot from it. Thank you! :-)

"10 milliseconds" is the time from the reference paper. In the initial implementation, we
used 10 seconds just to be on the safe side.

Regarding small file append, it starts from the correct offset in the tests I observed. For
example, I tried "echo abcd >> /mnt_test/file_with_5bytes", the write request starts
with offset 5. With the initial file loading tests with Linux/Mac clients, so far we haven't
encountered the problem you mentioned. 

For the second question, as long as the second user uses NFS gateway to read the closed file,
the second user should be able to get the data buffered in NFS gateway. For the opened files,
NFS gateway also saves their latest file size. When it serves getattr request, it gets file
attributes from HDFS and then update the file length based on the cached length.

Thanks!
Brandon


                
> 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 support 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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