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https://issues.apache.org/jira/browse/HADOOP-985?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Raghu Angadi updated HADOOP-985:
--------------------------------
Attachment: HADOOP-985-5.patch
5.patch : includes the changes Hairong suggested.
We now send hostname for hints. Thanks Ownen, verified that job tracker
correctly assigns the jobs.
> Namenode should identify DataNodes as ip:port instead of hostname:port
> ----------------------------------------------------------------------
>
> Key: HADOOP-985
> URL: https://issues.apache.org/jira/browse/HADOOP-985
> Project: Hadoop
> Issue Type: Improvement
> Components: dfs
> Affects Versions: 0.11.0
> Reporter: Raghu Angadi
> Assigned To: Raghu Angadi
> Fix For: 0.12.0
>
> Attachments: dfshealth.html, HADOOP-985-1.patch, HADOOP-985-2.patch,
> HADOOP-985-3.patch, HADOOP-985-4.patch, HADOOP-985-5.patch
>
>
> Right now NameNode keeps track of DataNodes with "hostname:port". One
> proposal is to keep track of datanodes with "ip:port". There are various
> concerns expressed regd hostnames and ip. Please add your experiences here so
> that we have better idea on what we should fix etc.
> How should be calculate datanode ip:
> 1) Just like how we calculate hostname currently with
> "dfs.datanode.dns.interface" and "dfs.datanode.dns.nameserver". So if
> interface specified wrong, it could report ip like 127.0.0.1 which might or
> might not be intended.
> 2) Namenode can use the remove socket address when the datanode
> registers. Not sure how easy it to get this address in RPC or if this is
> desirable.
> 3) Namenode could just resolve the hostname when a datanode
> registers. It could print of a warning if the resolved ip and reported ip
> don't match.
> One advantage of using IPs is that DFSClient does not need to resolve them
> when it connects to datanode. This could save few milliseconds for each
> block. Also, DFSClient should check all its ips to see if a given ip is local
> or not.
> As far I see namenode does not resolve any DNS in normal operations since it
> does not actively contact datanodes. In that sense not sure if this have any
> change in Namenode performance.
> Thoughts?
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