[jira] [Commented] (HDFS-4832) Namenode doesn't change the number of missing blocks in safemode when DNs rejoin or leave

["Ravi Prakash (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HDFS-4832?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13672659#comment-13672659 ] 

Ravi Prakash commented on HDFS-4832:
------------------------------------

bq. The computeReplicationWorkForBlocks() is called every replicationRecheckInterval which defaults to 3 seconds. Can we please handle this in a separate JIRA?
To correct myself, no more replication / invalidation work will be scheduled in safemode because computeDatanodeWork()'s very first statement checks for safemode. So we don't need any new JIRA.


                
> Namenode doesn't change the number of missing blocks in safemode when DNs rejoin or leave
> -----------------------------------------------------------------------------------------
>
>                 Key: HDFS-4832
>                 URL: https://issues.apache.org/jira/browse/HDFS-4832
>             Project: Hadoop HDFS
>          Issue Type: Bug
>    Affects Versions: 3.0.0, 0.23.7, 2.1.0-beta
>            Reporter: Ravi Prakash
>            Assignee: Ravi Prakash
>            Priority: Critical
>         Attachments: HDFS-4832.patch, HDFS-4832.patch, HDFS-4832.patch, HDFS-4832.patch
>
>
> Courtesy Karri VRK Reddy!
> {quote}
> 1. Namenode lost datanodes causing missing blocks
> 2. Namenode was put in safe mode
> 3. Datanode restarted on dead nodes 
> 4. Waited for lots of time for the NN UI to reflect the recovered blocks.
> 5. Forced NN out of safe mode and suddenly,  no more missing blocks anymore.
> {quote}
> I was able to replicate this on 0.23 and trunk. I set dfs.namenode.heartbeat.recheck-interval to 1 and killed the DN to simulate "lost" datanode. The opposite case also has problems (i.e. Datanode failing when NN is in safemode, doesn't lead to a missing blocks message)
> Without the NN updating this list of missing blocks, the grid admins will not know when to take the cluster out of safemode.

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