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From Evert Lammerts <Evert.Lamme...@sara.nl>
Subject Hadoop on Opennebula
Date Wed, 11 Nov 2009 10:42:56 GMT
Hi list,

 

We have a cluster with 44 cores on which we are evaluating OpenNebula. All
nodes run Ubuntu server 64bit. I'm trying to get Hadoop 0.20.1 to work, so
I'm following the cluster setup steps on hadoop.apache.org.

 

As a start I created three VM's running Ubuntu 9.10 32bit desktop edition.
After installing Sun's 1.6 JRE I put Hadoop into my homedir. I configured
the three installations of Hadoop as follows:

 

== conf/hadoop-env.sh ==

Set JAVA_HOME to the appropriate directory

 

== conf/core-site.xml ==

Set fs.default.name to the ip address of the designated namenode, on port
9000:

<property>

   <name>fs.default.name</name>

   <value>hdfs://XXX.XXX.X.XXX:9000/</value>

 </property>

 

== conf/hdfs-site.xml ==

Set dfs.name.dir to a directory in my homedir:

<property>

  <name>dfs.name.dir</name>

  <value>/home/cloud/var/log/hadoop/</value>

</property>

 

== conf/mapred-site.xml ==

Set mapred.job.tracker to the ip address of the designated jobtracker, on
port 9001:

<property>

  <name>mapred.job.tracker</name>

  <value>XXX.XXX.X.XXX:9001</value>

<property>

 

Apart from Hadoop configuration I manually set the hostname for the
namenode, jobtracker and slave (datanode & tasktracker) to respectively
hadoop-namenode, hadoop-jobtracker and hadoop-slave01.

 

I'm able to start the hdfs with bin/start-dfs.sh, and mapreduce with
bin/start-mapred.sh without any exceptions. However, when I now try to copy
files onto hdfs, I'm getting the following exception:

 

$ bin/hadoop fs -put conf input

09/11/11 05:24:47 WARN hdfs.DFSClient: DataStreamer Exception:
org.apache.hadoop.ipc.RemoteException: java.io.IOException: File
/user/cloud/input/capacity-scheduler.xml could only be replicated to 0
nodes, instead of 1

                at
org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNam
esystem.java:1267)

                at
org.apache.hadoop.hdfs.server.namenode.NameNode.addBlock(NameNode.java:422)

                at sun.reflect.GeneratedMethodAccessor20.invoke(Unknown
Source)

                at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl
.java:25)

                at java.lang.reflect.Method.invoke(Method.java:597)

                at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:508)

                at
org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:959)

                at
org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:955)

                at java.security.AccessController.doPrivileged(Native
Method)

                at javax.security.auth.Subject.doAs(Subject.java:396)

                at org.apache.hadoop.ipc.Server$Handler.run(Server.java:953)

 

                at org.apache.hadoop.ipc.Client.call(Client.java:739)

                at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:220)

                at $Proxy0.addBlock(Unknown Source)

                at sun.reflect.NativeMethodAccessorImpl.invoke0(Native
Method)

                at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39
)

                at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl
.java:25)

                at java.lang.reflect.Method.invoke(Method.java:597)

                at
org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocati
onHandler.java:82)

                at
org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHand
ler.java:59)

                at $Proxy0.addBlock(Unknown Source)

                at
org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.locateFollowingBlock(DFSCli
ent.java:2904)

                at
org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.nextBlockOutputStream(DFSCl
ient.java:2786)

                at
org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.access$2000(DFSClient.java:
2076)

                at
org.apache.hadoop.hdfs.DFSClient$DFSOutputStream$DataStreamer.run(DFSClient.
java:2262)

 

09/11/11 05:24:47 WARN hdfs.DFSClient: Error Recovery for block null bad
datanode[0] nodes == null

09/11/11 05:24:47 WARN hdfs.DFSClient: Could not get block locations. Source
file "/user/cloud/input/capacity-scheduler.xml" - Aborting...

put: java.io.IOException: File /user/cloud/input/capacity-scheduler.xml
could only be replicated to 0 nodes, instead of 1

 

Can anybody shed light on this? I'm guessing it's a configuration issue, so
that's the direction I'm looking at.

 

Another question I have is more generally about getting Hadoop to work on a
cloud. The issue I foresee is about the ip addresses of the masters and
slaves. How do I dynamically configure the hadoop instances during start-up
of the images to end up with a namenode, a jobtracker and a number of
slaves? I'll need the ip addresses of all machines and all machines need a
unique hostname. Does anybody have any experience with this?

 

Thanks in advance!

 

Evert Lammerts

Adviseur

SARA Computing & Network Services 

High Performance Computing & Visualization

eScience Support Group

 

Phone: +31 20 888 4101

Email: evert.lammerts@sara.nl

 


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