Hadoop NameNode Ip Address

Question

I'm using Hadoop MapReduce paradigm, and i need to get the NameNode IP address from the DataNode, can any one give me an idea how to do this?

Thanks.

score 7 · Answer 1 · answered Jun 04 '14 at 19:09

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Easiest way would be to quickly open the core-site.xml file under HADOOP_HOME/conf directory. The value of fs.default.name property will tell you the host and port where NN is running.

answered Jun 04 '14 at 19:09

Tariq

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The **fs.default.name** gives the Localhost of the DataNode Tarek.we can use this only in the namenode. – mohamus Jun 04 '14 at 19:26
That means you are running in pseudo distributed mode(All processes on a single machine). In this case the NN machine is same as the DN machine. – Tariq Jun 04 '14 at 19:28
No i used it on a multicluster hadoop, and when i try to get the IP addresse from the DataNode it gives me 127.0.0.1/localhost – mohamus Jun 04 '14 at 19:36
Could you please show me your **configuration files**, along with the **slaves** file present inside HADOOP_HOME/conf directory? – Tariq Jun 04 '14 at 19:37
fs.default.name hdfs://localhost:54310 – mohamus Jun 04 '14 at 19:44
slaves localhost slave slave2 slave3 slave4 – mohamus Jun 04 '14 at 19:45
Although your slaves file contains multiple hostnames, I doubt if it is actually a fully distributed setup. Could you please point your web browser to the NN webUI(NN_machine:50070) and make sure of this? – Tariq Jun 04 '14 at 19:51
localhost:50070 and the datanode – mohamus Jun 04 '14 at 21:00

score 1 · Answer 2 · edited Nov 21 '15 at 12:19

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Delete the line 127.0.0.1 localhost in your /etc/host and put your IP and the name of all your machines. Hadoop is resolving all the IPs and names of machines on the cluster as 127.0.0.1 localhost if you leave the file as default.

edited Nov 21 '15 at 12:19

Matthew Murdoch

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answered Jun 04 '14 at 21:21

Junayy

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this seems logique, i'll do that and give you the results. Regards. – mohamus Jun 04 '14 at 22:05
no error, the question was how to get the IP address of the namenode, and your solution still gives me the localhost address. – mohamus Jun 05 '14 at 12:11
I don't really understand ... It's you who define the ip adress of your machine ... no ? – Junayy Jun 05 '14 at 12:14
the problem is that i don't know if IP in a hadoop cluster, are static or DHCP? – mohamus Jun 05 '14 at 12:27
if they are static then the problem is resolved, otherwise i still have much work to do . – mohamus Jun 05 '14 at 12:28
You should go for static ip because Hadoop is very sensitive on ip. – Junayy Jun 05 '14 at 12:36
and for big hadoop clusters are they static or dynamic IPs ?? – mohamus Jun 05 '14 at 13:07
I don't know but trust me, it's very simpler in static IP ^^ – Junayy Jun 05 '14 at 13:12

Hadoop NameNode Ip Address

2 Answers2