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From "Craig Macdonald (JIRA)" <j...@apache.org>
Subject [jira] Commented: (PIG-102) Dont copy to DFS if source filesystem marked as shared
Date Fri, 07 Mar 2008 15:43:49 GMT

    [ https://issues.apache.org/jira/browse/PIG-102?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12576244#action_12576244
] 

Craig Macdonald commented on PIG-102:
-------------------------------------

HI Benjamin,

That's a simpler concept, which is easier to implement. 

The disadvantage is that is less transparent to the user. An administrator might set the sharedFS
globally,  while if we use the shared:/ prefix idea then the user has to remember about shared:/,
and make a decision for each job whether its a local file, a local-but-shared file or a DFS
file, instead of just the foremost and latter.

Craig

> Dont copy to DFS if source filesystem marked as shared
> ------------------------------------------------------
>
>                 Key: PIG-102
>                 URL: https://issues.apache.org/jira/browse/PIG-102
>             Project: Pig
>          Issue Type: New Feature
>          Components: impl
>         Environment: Installations with shared folders on all nodes (eg NFS)
>            Reporter: Craig Macdonald
>
> I've been playing with Pig using three setups:
> (a) local
> (b) hadoop mapred with hdfs
> (c) hadoop mapred with file:///path/to/shared/fs as the default file system
> In our local setup, various NFS filesystems are shared between all machines (including
mapred nodes)  eg /users, /local
> I would like Pig to note when input files are in a file:// directory that has been marked
as shared, and hence not copy it to DFS.
> Similarly, the Torque PBS resource manager has a usecp directive, which notes when a
filesystem location is shared between all nodes, (and hence scp is not needed, cp alone can
be used). See http://www.clusterresources.com/wiki/doku.php?id=torque:6.2_nfs_and_other_networked_filesystems
> It would be good to have a configurable setting in Pig that says when a filesystem is
shared, and hence no copying between file:// and hdfs:// is needed.
> An example in our setup might be:
> sharedFS file:///local/
> sharedFS file:///users/
> if commands should be used.
> This command should be used with care. Obviously if you have 1000 nodes all accessing
a shared file in NFS, then it would have been better to "hadoopify" the file.
> The likely area of code to patch is src/org/apache/pig/impl/io/FileLocalizer.java hadoopify(String,
PigContext)

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