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From "Dave Marion (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-118) accumulo could work across HDFS instances, which would help it to scale past a single namenode
Date Tue, 28 May 2013 16:40:20 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-118?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13668428#comment-13668428
] 

Dave Marion commented on ACCUMULO-118:
--------------------------------------

bq. Would avoding storing direct pointers to namenodes in the metadata table be sufficient
to satisfy this? Always have a level of indirection like viewfs? 

Yes, a simple direct mapping is what I would like to see. Using a hash function is not simple
or direct and I don't see why its needed. If I have a backup of the files from ns1 on ns2
and vice versa (think hot backup) and ns2 fails, then I can just change the mapping so that
both ns1 and ns2 point to the same Hadoop HDFS instance. No update of the metadata table needed.
                
> 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
>            Reporter: Eric Newton
>            Assignee: Eric Newton
>            Priority: Blocker
>             Fix For: 1.6.0
>
>         Attachments: ACCUMULO-118-01.txt
>
>   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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