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https://issues.apache.org/jira/browse/PIG-102?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12576769#action_12576769
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Pi Song commented on PIG-102:
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Just out of curiosity again. When Hadoop MapReduce runs using LocalFS. By
default, how do they transfer data between nodes?
Was this capability intended to be used in cases just like Craig's NFS?
> 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
> Attachments: shared.patch
>
>
> 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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