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https://issues.apache.org/jira/browse/HDFS-6186?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13998206#comment-13998206
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Hudson commented on HDFS-6186:
------------------------------

FAILURE: Integrated in Hadoop-Hdfs-trunk #1753 (See 
[https://builds.apache.org/job/Hadoop-Hdfs-trunk/1753/])
HDFS-6186. Pause deletion of blocks when the namenode starts up. Contributed by 
Jing Zhao. (jing9: 
http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1594314)
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
* 
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
* 
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java
* 
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/InvalidateBlocks.java
* 
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestPendingInvalidateBlock.java


> 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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