Is it necessary to have 2 linux machine for configuring two node hadoop cluster(ie 1 master 1 slave).Can it be done on single machine
Yes, you can run in local mode or pseudo-distributed mode, you don't necessarily need an actual cluster of machines.
See: http://hadoop.apache.org/docs/stable/single_node_setup.html
Related
I have a cluster of 3 macOS machines running Hadoop and Spark-1.5.2 (though with Spark-2.0.0 the same problem exists). With 'yarn' as the Spark master URL, I am running into a strange issue where tasks are only allocated to 2 of the 3 machines.
Based on the Hadoop dashboard (port 8088 on the master) it is clear that all 3 nodes are part of the cluster. However, any Spark job I run only uses 2 executors.
For example here is the "Executors" tab on a lengthy run of the JavaWordCount example:
"batservers" is the master. There should be an additional slave, "batservers2", but it's just not there.
Why might this be?
Note that none of my YARN or Spark (or, for that matter, HDFS) configurations are unusual, except provisions for giving the YARN resource- and node-managers extra memory.
Remarkably, all it took was a detailed look at the spark-submit help message to discover the answer:
YARN-only:
...
--num-executors NUM Number of executors to launch (Default: 2).
If I specify --num-executors 3 in my spark-submit command, the 3rd node is used.
I'm trying to install Hadoop in a virtual machine, I found a tutorial explaining how to do that in a multi-node cluster .
So my question is what's the difference between a single-node and a multi-node cluster ?
Thanks in advance :)
Single node cluster : By default, Hadoop is configured to run in a non-distributed or standalone mode, as a single Java process. There are no daemons running and everything runs in a single JVM instance. HDFS is not used.
Pseudo-distributed or multi-node cluster: The Hadoop daemons run on a local machine, thus simulating a cluster on a small scale. Different Hadoop daemons run in different JVM instances, but on a single machine. HDFS is used instead of local FS
And you can have your work environment set up as follow
Step 1 - Download VMware player latest version and install on your laptop/desktop. You can also install VMware tools, which will be very useful for your working with guest OS.
Step 2 - Once you Step 1 is completed then Download Cloudera Quick Start VM from
http://www.cloudera.com/content/support/en/downloads/download-components/download-products.html?productID=F6mO278Rvo
Step 3 - Open VMPlayer program and click on “Open a virtual Machine”. and go to directory “cloudera-quickstart-vm-4.4.0-1-vmware”. Select cloudera-quickstart-vm-4.4.0-1-vmware. This will create a virtual machine instance in VM Player.
Step 4 - Start the Cloudera VM by Clicking on power on to start the Cloudera Demo VM.
You are good to go
Good luck
Assume that there is a Hadoop Cluster that has 20 machines.
Out of those 20 machines 18 machines are slaves and machine 19 is for NameNode and machine 20 is for JobTracker.
My question is: In which machine out of these 20 machines do I need to install hadoop software?
Do I need to install Hadoop in all those 20 machines?
You need to install hadoop in all machines , u just need to make suitable changes in configuration files of namenode and datanode. You can refer Michall nolls Multi-node installation for the same.
I have 2 hadoop pseudo(standalone) servers, which I created for testing purposes.
Now I want to club the two servers into one cluster and make this a Master-Slave configuration.
Is there anyway to achieve this?
Thanks in advance.
Step 1
Determine which pseudo you want to be master. Once decided add master machine name in file
$hadoop_home/conf/master
Step 2
If u want other pseudo as well as master machine to act as DataNodes then add these machine names in file
$hadoop_home/conf/slaves
Step 3
Make SSH password less connection between master and slave. And change
/etc/hosts
file if necessary if they are getting connected.
Step 4
Now prepare the hadoop MultiNode Cluster to start
Format namenode
$hadoop_home/bin/hadoop namenode -format
Start the cluster
$hadoop_home/bin/start-all.sh
sure you can, just follow Running Hadoop on Ubuntu Linux (Multi-Node Cluster)
Pseudo-Distributed single node cluster implementation
I am using window 7 with CYGWIN and installed hadoop-1.0.3 successfully. I still start services job tracker,task tracker and namenode on port (localhost:50030,localhost:50060 and localhost:50070).I have completed single node implementation.
Now I want to implement Pseudo-Distributed multiple node cluster . I don't understand how to divide in master and slave system through network ips?
For your ssh problem just follow the link of single node cluster :
http://www.michael-noll.com/tutorials/running-hadoop-on-ubuntu-linux-single-node-cluster/
and yes, you need to specify the ip's of master and slave in conf file
for that you can refer this url :
http://www.michael-noll.com/tutorials/running-hadoop-on-ubuntu-linux-multi-node-cluster/
I hope this helps.
Try to create number of VM you want to add in your cluster.Make sure that those VM are having the same hadoop version .
Figure out the IPs of each VM.
you will find files named master and slaves in $HADOOP_HOME/conf mention the IP of VM to conf/master file which you want to treat as master and and do the same with conf/slaves
with slave nodes IP.
Make sure these nodes are having Passwordless-ssh connection.
Format your namenode and then run start-all.sh.
Thanks,