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What do you think of these three questions mentioned in site CCD-410 Practice Exam Questions Demo 100% Pass-Guaranteed or Your Money Back!!!

QUESTION: 3

What happens in a MapReduce job when you set the number of reducers to one?

A. A single reducer gathers and processes all the output from all the mappers. The output is written in as many separate files as there are mappers.
B. A single reducer gathers and processes all the output from all the mappers. The output is written to a single file in HDFS.
C. Setting the number of reducers to one creates a processing bottleneck, and since the number of reducers as specified by the programmer is used as a reference value only, the MapReduceruntime provides a default setting for the number of reducers.
D. Setting the number of reducers to one is invalid, and an exception is thrown.

Answer:A

QUESTION: 4

In the standard word count MapReduce algorithm, why might using a combiner reduce theoverall Job running time?

A. Because combiners perform local aggregation of word counts, thereby allowing the mappers to process input data faster.
B. Because combinersperform local aggregation of word counts, thereby reducing the number of mappers that need to run.
C. Because combiners perform local aggregation of word counts, and then transfer that data toreducers without writing the intermediate data to disk.
D. Because combiners perform local aggregation of word counts, thereby reducing the number of key-value pairs that need to be snuff let across the network to the reducers.

Answer:A

QUESTION: 5

You have user profile records in your OLTP database,that you want to join with weblogs you have already ingested into HDFS.How will you obtain these user records?

A. HDFS commands
B. Pig load
C. Sqoop import
D. Hive

Answer :B


Correct Answers

QUESTION 3: Answer B
QUESTION 4: Answer D
QUESTION 5: Answer C

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Hadoop Installation Using Cloudera Package - Pseudo Distributed Mode (Single Node)

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Hadoop can be installed using cloudera also with less steps in an easy way .The difference is Cloudera packed Apache Hadoop and some ecosystem projects into one package.And they have set all the configuration to localhost and we need not want to set the configuration files.

Installation using Cloudera Package.

Prerequistie

1.Java

Installation Steps

Step 1: Set Java home in /etc/profile

unmesha@unmesha-hadoop-virtual-machine:~$ java -version
java version "1.7.0_55"
Java(TM) SE Runtime Environment (build 1.7.0_55-b13)
Java HotSpot(TM) 64-Bit Server VM (build 24.55-b03, mixed mode)

Check your current location of java 

unmesha@unmesha-hadoop-virtual-machine:~$ sudo update-alternatives --config java
[sudo] password for unmesha: 
There is only one alternative in link group java: /usr/lib/jvm/java-7-oracle/jre/bin/java
Nothing to configure.

Set JAVA_HOME

export JAVA_HOME=/usr/lib/jvm/java-7-oracle

unmesha@unmesha-hadoop-virtual-machine:~$ source ~/.bashrc 

Step 2: Download the package for your system under "On Ubuntu and other Debian systems, do the following:" heading from here.

Step 3: Extract the package

unmesha@unmesha-hadoop-virtual-machine:~$sudo dpkg -i cdh4-repository_1.0_all.deb

Step 4: Install Hadoop

unmesha@unmesha-hadoop-virtual-machine:~$sudo apt-get update 
unmesha@unmesha-hadoop-virtual-machine:~$sudo apt-get install hadoop-0.20-conf-pseudo

Step 5: Format Namenode

unmesha@unmesha-hadoop-virtual-machine:~$sudo -u hdfs hdfs namenode -format

Step 6: Start HDFS

unmesha@unmesha-hadoop-virtual-machine:~$for x in `cd /etc/init.d ; ls hadoop-hdfs-*` ; do sudo service $x start ; done

Step 7: Create the /tmp Directory

unmesha@unmesha-hadoop-virtual-machine:~$sudo -u hdfs hadoop fs -mkdir /tmp 
unmesha@unmesha-hadoop-virtual-machine:~$sudo -u hdfs hadoop fs -chmod -R 1777 /tmp

Step 8: Create the MapReduce system directories

unmesha@unmesha-hadoop-virtual-machine:~$sudo -u hdfs hadoop fs -mkdir -p /var/lib/hadoop-hdfs/cache/mapred/mapred/staging

unmesha@unmesha-hadoop-virtual-machine:~$sudo -u hdfs hadoop fs -chmod 1777 /var/lib/hadoop-hdfs/cache/mapred/mapred/staging

unmesha@unmesha-hadoop-virtual-machine:~$sudo -u hdfs hadoop fs -chown -R mapred /var/lib/hadoop-hdfs/cache/mapred

Step 9: Verify the HDFS File Structure

unmesha@unmesha-hadoop-virtual-machine:~$sudo -u hdfs hadoop fs -ls -R /

Step 10: Start MapReduce

unmesha@unmesha-hadoop-virtual-machine:~$for x in `cd /etc/init.d ; ls hadoop-0.20-mapreduce-*` ; do sudo service $x start ; done

Step 11: Set up user directory

unmesha@unmesha-hadoop-virtual-machine:~$sudo -u hdfs hadoop fs -mkdir /user/<your username>unmesha@unmesha-hadoop-virtual-machine:~$sudo -u hdfs hadoop fs -chown <user> /user/<your username> 
unmesha@unmesha-hadoop-virtual-machine:~$sudo -u hdfs hadoop fs -mkdir /user/unmesha/new

Step 12: Run grep example, you can also try out wordcount example

unmesha@unmesha-hadoop-virtual-machine:~$/usr/bin/hadoop jar /usr/lib/hadoop-0.20-mapreduce/hadoop-examples.jar grep input output 'dfs[a-z.]+'

Step 13: You can also stop the services

unmesha@unmesha-hadoop-virtual-machine:~$for x in `cd /etc/init.d ; ls hadoop-hdfs-*` ; do sudo service $x stop ; done

unmesha@unmesha-hadoop-virtual-machine:~$for x in `cd /etc/init.d ; ls hadoop-0.20-mapreduce-*` ; do sudo service $x stop ; done

Happy Hadooping ...