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From "Raju (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-3744) Decommissioned nodes are included in cluster after switch which is not expected
Date Wed, 01 Aug 2012 17:49:04 GMT

    [ https://issues.apache.org/jira/browse/HDFS-3744?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13426775#comment-13426775
] 

Raju commented on HDFS-3744:
----------------------------

{quote}We have to execute this particular command on both the nodes.
Otherwise, even though we make it failover work here, still SNN will not know about the excluded
nodes as it did not get any refresh nodes command.
{quote}
Until SNN gets refreshnodes command SNN will not be aware of decommission of DN. But if we
send the command to SNN as well which will cause the REPLICATION triggered in the SNN as well.
Even though DN will not accept any requests from SNN, but SNN will be trying to replicate
the blocks which will increase the load on SNN + N/W load + DN load as well.

This is my initial opinion, Please let me know if my opinion is wrong. 

                
> Decommissioned nodes are included in cluster after switch which is not expected
> -------------------------------------------------------------------------------
>
>                 Key: HDFS-3744
>                 URL: https://issues.apache.org/jira/browse/HDFS-3744
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: ha
>    Affects Versions: 2.0.0-alpha, 2.1.0-alpha, 2.0.1-alpha
>            Reporter: Brahma Reddy Battula
>
> Scenario:
> =========
> Start ANN and SNN with three DN's
> Exclude DN1 from cluster by using decommission feature 
> (./hdfs dfsadmin -fs hdfs://ANNIP:8020 -refreshNodes)
> After decommission successful,do switch such that SNN will become Active.
> Here exclude node(DN1) is included in cluster.Able to write files to excluded node since
it's not excluded.
> Checked SNN(Which Active before switch) UI decommissioned=1 and ANN UI 
> decommissioned=0
> One more Observation:
> ====================
> All dfsadmin commands will create proxy only on nn1 irrespective of Active or standby.I
think this also we need to re-look once..
> I am not getting , why we are not given HA for dfsadmin commands..?
> Please correct me,,If I am wrong.

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