[jira] Commented: (HADOOP-4103) Alert for missing blocks

["dhruba borthakur (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-4103?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12788946#action_12788946 ] 

dhruba borthakur commented on HADOOP-4103:
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I am seeing that the "dfsadmin -report" reports widely fluctuating values for missing blocks. If I run the command twice successively within 10 seconds , each run shows different values, sometimes 20, sometimes 48, etc.etc. Is it because the method BlocksManager.getMissingBlocksCount() does not do any locking? Will it help to declare "volatile" for BlockManager.missingBlocksInCurIter and BlockManager.missingBlocksInPrevIter?

> Alert for missing blocks
> ------------------------
>
>                 Key: HADOOP-4103
>                 URL: https://issues.apache.org/jira/browse/HADOOP-4103
>             Project: Hadoop Common
>          Issue Type: New Feature
>    Affects Versions: 0.17.2
>            Reporter: Christian Kunz
>            Assignee: Raghu Angadi
>             Fix For: 0.20.0
>
>         Attachments: HADOOP-4103-branch-20.patch, HADOOP-4103.patch, HADOOP-4103.patch, HADOOP-4103.patch, HADOOP-4103.patch
>
>
> A whole bunch of datanodes became dead because of some network problems resulting in  heartbeat timeouts although datanodes were fine.
> Many processes started to fail because of the corrupted filesystem.
> In order to catch and diagnose such problems faster the namenode should detect the corruption automatically and provide a way to alert operations. At the minimum it should show the fact of corruption on the GUI.

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