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https://issues.apache.org/jira/browse/HADOOP-785?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12525491
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Doug Cutting commented on HADOOP-785:
-------------------------------------

> That would argue for per-file permissions rather than per-directory. Hmm. 
> Time to comment on HADOOP-1298...

Nevermind.  We can simply store all job-specific data in a sub-directory of the 
system dir that's owned by the job's user.  The client writes it there, and the 
task reads it.  We just need to make the system directory world-writable so 
that clients can create jobs there, and the clients can set their job 
directories world-unreadable.  We can use group permissions to permit the 
jobtracker to read the job.xml.  So per-directory permissions are sufficient.

> Divide the server and client configurations
> -------------------------------------------
>
>                 Key: HADOOP-785
>                 URL: https://issues.apache.org/jira/browse/HADOOP-785
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: conf
>    Affects Versions: 0.9.0
>            Reporter: Owen O'Malley
>            Assignee: Arun C Murthy
>             Fix For: 0.15.0
>
>         Attachments: HADOOP-785_1_20070903.patch, HADOOP-785_2_20070906.patch
>
>
> The configuration system is easy to misconfigure and I think we need to 
> strongly divide the server from client configs. 
> An example of the problem was a configuration where the task tracker has a 
> hadoop-site.xml that set mapred.reduce.tasks to 1. Therefore, the job tracker 
> had the right number of reduces, but the map task thought there was a single 
> reduce. This lead to a hard to find diagnose failure.
> Therefore, I propose separating out the configuration types as:
> class Configuration;
> // reads site-default.xml, hadoop-default.xml
> class ServerConf extends Configuration;
> // reads hadoop-server.xml, $super
> class DfsServerConf extends ServerConf;
> // reads dfs-server.xml, $super
> class MapRedServerConf extends ServerConf;
> // reads mapred-server.xml, $super
> class ClientConf extends Configuration;
> // reads hadoop-client.xml, $super
> class JobConf extends ClientConf;
> // reads job.xml, $super
> Note in particular, that nothing corresponds to hadoop-site.xml, which 
> overrides both client and server configs. Furthermore, the properties from 
> the *-default.xml files should never be saved into the job.xml.

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