[jira] [Commented] (ACCUMULO-118) accumulo could work across HDFS instances, which would help it to scale past a single namenode

["Eric Newton (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ACCUMULO-118?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13411597#comment-13411597 ] 

Eric Newton commented on ACCUMULO-118:
--------------------------------------

I'm leaning towards using full-paths for filenames, and having the system select a path based on a pluggable component.  The NN references would be handled by viewfs and federation.

This will be an extensive change, and it's going to take a while to refactor the code to deal with full paths.

There are a bunch of places where we rely on {{rename()}} being inexpensive. If we move something from {{/nn1/accumulo/tables}} to {{//nn2/accumulo/tables}} that will be expensive.  Usually we are just renaming a file from {{foo.tmp}} to {{foo}}, which will work fine.  But there are others:

 * bulk import
 * log archiving
 * others?

these renames will need to be namespace aware.

                
> accumulo could work across HDFS instances, which would help it to scale past a single namenode
> ----------------------------------------------------------------------------------------------
>
>                 Key: ACCUMULO-118
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-118
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: master, tserver
>    Affects Versions: 1.5.0
>            Reporter: Eric Newton
>            Assignee: Eric Newton
>   Original Estimate: 2,016h
>  Remaining Estimate: 2,016h
>
> Consider using full path names to files, which would allow the servers to access the files on any HDFS file system.
> Work may exist elsewhere to run HDFS using a number of NameNode instances to break up the namespace.
> We may need a pluggable strategy to determine namespace for new files.

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