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From "Matt Foley (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (AMBARI-12138) Set dfs.client.retry.policy.enabled property to true when HDFS HA is enabled
Date Fri, 10 Jul 2015 16:50:04 GMT

    [ https://issues.apache.org/jira/browse/AMBARI-12138?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14622578#comment-14622578
] 

Matt Foley commented on AMBARI-12138:
-------------------------------------

This jira overlaps with AMBARI-11192 - The Default hdfs-site.xml Should Have Client Retry
Logic Enabled For Rolling Upgrade.
Different reason, same intended change.

However, that patch was implemented, then reverted for the reasons given here: https://issues.apache.org/jira/browse/AMBARI-11192?focusedCommentId=14615924&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14615924
It turns out that the stuff that happens under the covers when dfs.client.retry.policy.enabled
is set to true in an HA environment, have a bad side effect: If a primary NN is killed "dirty",
then clients attempting to connect to it have a 10 minute delay before switching over to the
new NN.  So the underlying mechanisms need to be fixed before dfs.client.retry.policy.enabled
can be safely set to true for HA clusters.

In the meantime, HA seems to work as expected even with dfs.client.retry.policy.enabled set
to false.


> Set dfs.client.retry.policy.enabled property to true when HDFS HA is enabled
> ----------------------------------------------------------------------------
>
>                 Key: AMBARI-12138
>                 URL: https://issues.apache.org/jira/browse/AMBARI-12138
>             Project: Ambari
>          Issue Type: Improvement
>          Components: ambari-web
>    Affects Versions: 2.1.0
>            Reporter: sam liu
>         Attachments: AMBARI-12138.patch
>
>
> After enabling HDFS HA, hdfs-site.xml does not include property  dfs.client.retry.policy.enabled
and 'hdfs getconf -confKey dfs.client.retry.policy.enabled' returns empty value. 
> The property dfs.client.retry.policy.enabled is important when HA is enabled, as it enables
HDFS client retry in case of NameNode failure. So, after enabling HDFS HA, Ambari should set
this property to true in hdfs-site.xml.



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