How Combiner works in Hadoop MapReduce

Hadoop is a framework used for handling Big Data. It uses HDFS as the distributed storage mechanism and MapReduce as the parallel processing paradigm for data residing in HDFS. The key components of Mapreduce are Mapper and Reducer. When a MapReduce Job runs on a large dataset, Mappers generate large […]

Importing Data using Sqoop

Sqoop is an Apache Hadoop top-level project and designed to move data between Hadoop and RDBMS. Sqoop is a collection of related tools. To use Sqoop, you specify the tool you want to use and the arguments that control the tool.

In this post, we will cover how to […]

Introduction to Sqoop and Installation

To process and analyze data in Hadoop, it requires loading data into Hadoop file system that is present on Application server and databases. Sqoop is a tool designed to transfer data between Hadoop and relational databases or mainframes. You can use Sqoop to import data from a relational database management […]

Working with HDFS Snapshots

This blog gives an overview of HDFS snapshots and different operations that users / cluster administrators can perform related to HDFS snapshots. It also explains snapshot management through Cloudera Manager. Overview of HDFS Snapshots Snapshots are data backup for protection against user errors and disaster recovery. Snapshots can be taken on a sub-tree of […]

Passwordless SSH between linux machines

Passwordless SSH (Secure Shell) between two machines is required by a lot of distributed frameworks. It creates a secure shell connection from the host machine to the remote machine without password prompt. Follow the steps below to configure Passwordless SSH between two linux machines. Prerequisites 1. Install Open SSH Server package on […]

Big Data – Hadoop Interview Questions

To crack an interview, it is must that your basic concepts about frameworks are pretty clear. On request of many of our students, we’ve put together a comprehensive list of questions to help you get through your Big Data – Hadoop interview. We’ve made sure that the most probable questions […]

Start HDFS High Availability Cluster

In the previous blog, we discussed about the HDFS high availability configuration. This blog describes the steps to start an HDFS high availability cluster. Pre-requisites Before starting with HDFS high availability cluster, make sure that the cluster meets the following pre-requisites: a)  If you have enabled Automatic Failover for Hot-BackUp during NameNode failover,  then before starting with HDFS high availability cluster, […]

HDFS High Availability Configuration

In the previous blog, we discussed about the HDFS High availability architecture. This blog describes the configurations for HDFS high availability in a Hadoop cluster. Pre-requisites Before configuring HDFS high availability, make sure that your Hadoop cluster has the following pre-requisites: a) You must have at-least two nodes to enable HDFS high availability. b) If you want to configure […]