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https://issues.apache.org/jira/browse/HDFS-6186?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jing Zhao updated HDFS-6186:
----------------------------

       Resolution: Fixed
    Fix Version/s: 2.5.0
     Hadoop Flags: Reviewed
           Status: Resolved  (was: Patch Available)

Thanks for the review again, Suresh! I've committed this to trunk and branch-2. 
I've also created HDFS-6385 for showing the pending deletion information in Web 
UI.

> Pause deletion of blocks when the namenode starts up
> ----------------------------------------------------
>
>                 Key: HDFS-6186
>                 URL: https://issues.apache.org/jira/browse/HDFS-6186
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: namenode
>            Reporter: Suresh Srinivas
>            Assignee: Jing Zhao
>             Fix For: 2.5.0
>
>         Attachments: HDFS-6186.000.patch, HDFS-6186.002.patch, 
> HDFS-6186.003.patch
>
>
> HDFS namenode can delete blocks very quickly, given the deletion happens as a 
> parallel operation spread across many datanodes. One of the frequent 
> anxieties I see is that a lot of data can be deleted very quickly, when a 
> cluster is brought up, especially when one of the storage directories has 
> failed and namenode metadata was copied from another storage. Copying wrong 
> metadata would results in some of the newer files (if old metadata was 
> copied) being deleted along with their blocks. 
> HDFS-5986 now captures the number of pending deletion block on namenode webUI 
> and JMX. I propose pausing deletion of blocks for a configured period of time 
> (default 1 hour?) after namenode comes out of safemode. This will give enough 
> time for the administrator to notice large number of pending deletion blocks 
> and take corrective action.
> Thoughts?



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