1 What is a distributed file system?
A distributed file system is an application that stores the files across cluster nodes and allows the clients to access the files from the cluster. Though physically the files are distributed across the nodes, logically it appears to the client as if the files are residing on their local machine.
2 What is failover?
Failover is the process of switching to a redundant node upon the abnormal ter- mination or failure of a previously active node.
3 What is the difference between failover and switch over?
Failover is an automatic mechanism that does not require any human intervention.
This differentiates it from the switch over operation, which essentially requires human intervention.
4 What are the types of cluster?
There are types of cluster
● High-availability cluster
● Load-balancing cluster
5 What is a high-availability cluster?
High availability clusters are designed to minimize downtime and provide unin- terrupted service when nodes fail. Nodes in a highly available cluster must have
access to a shared storage. Such systems are often used for failover and backup purposes.
6 What is a load-balancing cluster?
Load balancing clusters are designed to distribute workloads across different clus- ter nodes to share the service load among the nodes. The main objective of load balancing is to optimize the use of resources, minimize response time, maximize throughput, and avoid overload on any one of the resources.
7 What is a symmetric cluster?
Symmetric cluster is a type of cluster structure in which each node functions as an individual computer capable of running applications.
8 What is an asymmetric cluster?
Asymmetric cluster is a type of cluster structure in which one machine acts as the head node, and it serves as the gateway between the user and the remain- ing nodes.
9 What is sharding?
Sharding is the process of partitioning very large data sets into smaller and easily manageable chunks called shards. The partitioned shards are stored by distribut- ing them across multiple machines called nodes. No two shards of the same file are stored in the same node, each shard occupies separate nodes, and the shards spread across multiple nodes collectively constitute the data set.
10 What is Replication?
Replication is the process of copying the same data blocks across multiple nodes to overcome the loss of data when a node crashes. The copy of a data block is called replica. Replication makes the system fault tolerant since the data is not lost when an individual node fails as the data is redundant across the nodes.
11 What is the difference between replication and sharding?
Replication copies the same data blocks across multiple nodes whereas sharding copies different data across different nodes.
12 What is the master-slave model?
Master-slave configuration is a model where one centralized device known as the master controls one or more devices known as slaves.
13 What is the peer-to-peer model?
In a peer-to-peer configuration there is no master-slave concept, all the nodes have the same responsibility and are at the same level.
14 What is scaling up?
Scaling-up, the vertical scalability, adds more resources to the existing server to increase its capacity to hold more data. The resources can be computation power, hard drive, RAM, and so on. This type of scaling is limited to the maximum scaling capacity of the server.
15 What is Scaling-out?
Scaling out, the horizontal scalability, adds new servers or components to meet the demand. The additional component added is termed as node. Big data technologies work on the basis of scaling out storage. Horizontal scaling enables the system to scale wider to meet the increasing demand. Scaling out storage uses low cost commodity hardware and storage components. The components can be added as required without much complexity. Multiple components connect together to work as a single entity.
16 What is a NewSQL database?
A NewSQL database is designed to provide scalable performance similar to that of NoSQL systems combining the ACID (atomicity, consistency, isolation, and dura- bility), properties of a traditional database management system.
Big Data: Concepts, Technology, and Architecture, First Edition. Balamurugan Balusamy, Nandhini Abirami. R, Seifedine Kadry, and Amir H. Gandomi.
© 2021 John Wiley & Sons, Inc. Published 2021 by John Wiley & Sons, Inc.
3.1 Introduction to NoSQL
In day-to-day operations massive data is generated from all sources in different formats. Bringing together this data for processing and analysis demands a flexi- ble storage system that can accommodate this massive data with varying formats.
The NoSQL database is designed in a way that it is best suitable to meet the big data processing demands.
NoSQL is a technology that represents a class of products that does not follow RDBMS principles and are often related to storage and retrieval of massive vol- umes of data. They find their applications in big data and other real-time web applications. Horizontal scalability, flexible schema, reliability, and fault tolerance are some of the features of NoSQL databases. NoSQL databases are structured in one of the following ways: key-value pairs, document-oriented database, graph database, or column-oriented database.