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Date: Wed, 27 Feb 2008 03:57:51 -0800 (PST)
From: "Hemanth Yamijala (JIRA)" <jira@apache.org>
To: core-dev@hadoop.apache.org
Subject: [jira] Commented: (HADOOP-2899) hdfs:///mapredsystem directory not
 cleaned up after deallocation
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    [ https://issues.apache.org/jira/browse/HADOOP-2899?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12572885#action_12572885 ] 

Hemanth Yamijala commented on HADOOP-2899:
------------------------------------------

Possible solutions:

1. The directory is world-readable. In HADOOP-1873, Doug commented that this should not be world-readable, so I guess this is not an option, for some reason.
2. JobTracker can delete the directory when it is shutdown. This seems, IMO, the best solution. Whoever creates, deletes.
3. HOD can create a directory that's specific to the user, something like mapredsystem/user-name.clusterid, where clusterid could be like a torque jobid. This may create a huge number of directories in HDFS, don't know if that's an issue. Otherwise, this is probably the *easiest* solution to implement
4. HOD can delete the mapredsystem directory at deallocation. This seems wrong, because it doesn't create it, and further, given our current design, this is very hard to implement.
5. JobTracker can avoid cleaning up the directory at startup. This may not be safe, in case there's a crash or something.

Comments ? 

> hdfs:///mapredsystem directory not cleaned up after deallocation 
> -----------------------------------------------------------------
>
>                 Key: HADOOP-2899
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2899
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: contrib/hod
>    Affects Versions: 0.16.0
>            Reporter: Luca Telloli
>
> Each submitted job creates a hdfs:///mapredsystem directory, created by (I guess) the hodring process. Problem is that it's not cleaned up at the end of the process; a use case would be:
> - user A allocates a cluster, the hodring is svrX, so a /mapredsystem/srvX directory is created
> - user A deallocates the cluster, but that directory is not cleaned up
> - user B allocates a cluster, and the first node chosen as hodring is svrX, so hodring tries to write hdfs:///mapredsystem but it fails
> - allocation succeeds, but there's no hodring running; looking at
> 0-jobtracker/logdir/hadoop.log under the temporary directory I can read:
> 2008-02-26 17:28:42,567 WARN org.apache.hadoop.mapred.JobTracker: Error starting tracker: org.apache.hadoop.ipc.RemoteException: org.apache.hadoop.fs.permission.AccessControlException: Permission denied: user=B, access=WRITE, inode="mapredsystem":hadoop:supergroup:rwxr-xr-x
> I guess a possible solution would be to clean up those directories during the deallocation process. 

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