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There are no errors in any log but I believe my datanode cannot find my namenode.

This is the error that leads me to this conclusion (according to what I've found online):

[INFO ]: org.apache.hadoop.ipc.Client - Retrying connect to server: /hadoop.server:9000. Already tried 4 time(s).

jps output:

7554 Jps
7157 NameNode
7419 SecondaryNameNode
7251 DataNode

Please can someone offer some advice?

Result of dfsadmin

Configured Capacity: 13613391872 (12.68 GB)
Present Capacity: 9255071744 (8.62 GB)
DFS Remaining: 9254957056 (8.62 GB)
DFS Used: 114688 (112 KB)
DFS Used%: 0.00%
Under replicated blocks: 0
Blocks with corrupt replicas: 0
Missing blocks: 0

-------------------------------------------------
Datanodes available: 1 (1 total, 0 dead)

Live datanodes:
Name: 192.172.1.49:50010 (Hadoop)
Hostname: Hadoop
Decommission Status : Normal
Configured Capacity: 13613391872 (12.68 GB)
DFS Used: 114688 (112 KB)
Non DFS Used: 4358320128 (4.06 GB)
DFS Remaining: 9254957056 (8.62 GB)
DFS Used%: 0.00%
DFS Remaining%: 67.98%
Configured Cache Capacity: 0 (0 B)
Cache Used: 0 (0 B)
Cache Remaining: 0 (0 B)
Cache Used%: 100.00%
Cache Remaining%: 0.00%
Last contact: Fri Aug 08 17:25:57 SAST 2014
Ree
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  • Please give more details of Error message – Abhishek Aug 08 '14 at 14:55
  • i extended the error message. it just repeats. its not actually an error message... just info (just realised). there is no error message anywhere... – Ree Aug 08 '14 at 14:58
  • hadoop dfsadmin -report .Try this command.It should show report of connected nodes – Abhishek Aug 08 '14 at 15:02
  • I had similar issues that ended up being from an incorrect /etc/hosts file. – lhoworko Aug 08 '14 at 15:24
  • added the dfsadmin output – Ree Aug 08 '14 at 15:34
  • what was wrong the with /etc/hosts file? mine has only 2 lines: 127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6 – Ree Aug 08 '14 at 15:35
  • Looks fine. Are you able to put files into the hdfs? – Abhishek Aug 08 '14 at 16:44
  • yes I can. i'm trying to connect from a client on another machine but i can't seem to be able to... – Ree Aug 08 '14 at 16:53
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    Can you check that NameNode is listening on non-localhost address (non 127.0.0.1)? Namenode's port is 8020 or 9000. – alvits Aug 09 '14 at 00:28
  • I have written one answer. See if that helps. – Abhishek Aug 09 '14 at 04:07
  • This post might help http://stackoverflow.com/questions/8872807/hadoop-datanodes-cannot-find-namenode. – raka Mar 28 '15 at 22:24

2 Answers2

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Give a hostname to your machines and make their entries in the /etc/hosts file, like this ,

#hostname hdserver.example.com
#vim /etc/hosts
192.168.0.25 hdserver.example.com
192.168.0.30 hdclient.example.com

and save it.(Use correct IP addresses)

On client also give hostname hdclient.example.com and make above entries in /etc/hosts. This will help the nameserver to locate the machines with hostnames.

Abhishek
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delete all contents from tmp folder: rm -Rf path/of/tmp/directory

format namenode: :bin/hadoop namenode -format

start all processes again : bin/start-all.sh

Saran Reddy
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