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You're reading from  Hadoop Real-World Solutions Cookbook - Second Edition

Product typeBook
Published inMar 2016
Publisher
ISBN-139781784395506
Edition2nd Edition
Tools
HadoopEclipse
Concepts
Data Processing
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Author (1)
Tanmay Deshpande
Tanmay Deshpande
author image
Tanmay Deshpande

Tanmay Deshpande is a Hadoop and big data evangelist. He currently works with Schlumberger as a Big Data Architect in Pune, India. He has interest in a wide range of technologies, such as Hadoop, Hive, Pig, NoSQL databases, Mahout, Sqoop, Java, cloud computing, and so on. He has vast experience in application development in various domains, such as oil and gas, finance, telecom, manufacturing, security, and retail. He enjoys solving machine-learning problems and spends his time reading anything that he can get his hands on. He has great interest in open source technologies and has been promoting them through his talks. Before Schlumberger, he worked with Symantec, Lumiata, and Infosys. Through his innovative thinking and dynamic leadership, he has successfully completed various projects. He regularly blogs on his website http://hadooptutorials.co.in. You can connect with him on LinkedIn at https://www.linkedin.com/in/deshpandetanmay/. He has also authored Mastering DynamoDB, published in August 2014, DynamoDB Cookbook, published in September 2015, Hadoop Real World Solutions Cookbook-Second Edition, published in March 2016, Hadoop: Data Processing and Modelling, published in August, 2016, and Hadoop Blueprints, published in September 2016, all by Packt Publishing.
Read more about Tanmay Deshpande

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Recycling deleted data from trash to HDFS

In this recipe, we are going to see how to recover deleted data from the trash to HDFS.

Getting ready

To perform this recipe, you should already have a running Hadoop cluster.

How to do it...

To recover accidently deleted data from HDFS, we first need to enable the trash folder, which is not enabled by default in HDFS. This can be achieved by adding the following property to core-site.xml:

<property>
    <name>fs.trash.interval</name>
    <value>120</value>
</property>

Then, restart the HDFS daemons:

/usr/local/hadoop/sbin/stop-dfs.sh
/usr/local/hadoop/sbin/start-dfs.sh

This will set the deleted file retention to 120 minutes.

Now, let's try to delete a file from HDFS:

hadoop fs -rmr /LICENSE.txt
    15/10/30 10:26:26 INFO fs.TrashPolicyDefault: Namenode trash configuration: Deletion interval = 120 minutes, Emptier interval = 0 minutes.
    Moved: 'hdfs://localhost:9000/LICENSE.txt' to trash at: hdfs://localhost:9000/user...
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Hadoop Real-World Solutions Cookbook - Second Edition
Published in: Mar 2016Publisher: ISBN-13: 9781784395506
© 2016 Packt Publishing Limited All Rights Reserved

Author (1)

author image
Tanmay Deshpande

Tanmay Deshpande is a Hadoop and big data evangelist. He currently works with Schlumberger as a Big Data Architect in Pune, India. He has interest in a wide range of technologies, such as Hadoop, Hive, Pig, NoSQL databases, Mahout, Sqoop, Java, cloud computing, and so on. He has vast experience in application development in various domains, such as oil and gas, finance, telecom, manufacturing, security, and retail. He enjoys solving machine-learning problems and spends his time reading anything that he can get his hands on. He has great interest in open source technologies and has been promoting them through his talks. Before Schlumberger, he worked with Symantec, Lumiata, and Infosys. Through his innovative thinking and dynamic leadership, he has successfully completed various projects. He regularly blogs on his website http://hadooptutorials.co.in. You can connect with him on LinkedIn at https://www.linkedin.com/in/deshpandetanmay/. He has also authored Mastering DynamoDB, published in August 2014, DynamoDB Cookbook, published in September 2015, Hadoop Real World Solutions Cookbook-Second Edition, published in March 2016, Hadoop: Data Processing and Modelling, published in August, 2016, and Hadoop Blueprints, published in September 2016, all by Packt Publishing.
Read more about Tanmay Deshpande

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