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Posted to hdfs-dev@hadoop.apache.org by "Uma Maheswara Rao G (Resolved) (JIRA)" <ji...@apache.org> on 2012/01/24 10:18:42 UTC
[jira] [Resolved] (HDFS-2713) HA : An alternative approach to
clients handling Namenode failover.
[ https://issues.apache.org/jira/browse/HDFS-2713?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Uma Maheswara Rao G resolved HDFS-2713.
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Resolution: Won't Fix
> HA : An alternative approach to clients handling Namenode failover.
> --------------------------------------------------------------------
>
> Key: HDFS-2713
> URL: https://issues.apache.org/jira/browse/HDFS-2713
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: ha, hdfs client
> Affects Versions: HA branch (HDFS-1623)
> Reporter: Uma Maheswara Rao G
> Assignee: Uma Maheswara Rao G
>
> This is the approach for client failover which we adopted when we developed HA for Hadoop. I would like to propose thia approach for others to review & include in the HA implementation, if found useful.
> This is similar to the ConfiguredProxyProvider in the sense that the it takes the address of both the Namenodes as the input. The major differences I can see from the current implementation are
> 1) During failover, user threads can be controlled very accurately about *the time they wait for active namenode* to be available, awaiting the retry. Beyond this, the threads will not be made to wait; DFS Client will throw an Exception indicating that the operation has failed.
> 2) Failover happens in a seperate thread, not in the client application threads. The thread will keep trying to find the Active Namenode until it succeeds.
> 3) This also means that irrespective of whether the operation's RetryAction is RETRY_FAILOVER or FAIL, the user thread can trigger the client's failover.
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