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Top1. Introduction
Cloud computing is an advanced step to parallel and distributed computing. It allows omnipresent access to the cluster of computing resources that exists in the data center (Banerjee, et al., 2015). The resources are in the form of computing capabilities, storage services, network services, bandwidth, and virtual machines or instances and are easily available via the internet services as per the billing metered of cloud vendors like Azure, Amazon, and Google Cloud (Gou, et al., 2016). With the revolutionary development in the IT industry and all the utilities of people, life produces large scale data all the time and often share Internet resources. This requires large bandwidth, storage, and processing elements that draw our attention from the traditional computing environment to data-centric computing for the execution of this large amount of data (Alworafi, et. al, 2019). It is beneficial from single users to large enterprise applications in the situation to need any kind of computing resources. It reduces the complexity of building the infrastructure and how they maintained. It is the responsibility of a cloud vendor that provided any kind of computing resources according to user requirements and also for enterprise applications based on the billing metered scale (Islam & Buyaa, 2019). A user task is submitted and executed on vendor resources. The services offered by cloud vendor under the various QoS parameter based on arbitration between cloud vendor and user. Cloud interconnect dynamic and malleable massive services that give a complete stack of services in the business market place. The core of the stack is infrastructure as a service (IaaS); Virtualized server, network services, storage, and processing capability are valuable services provided under IaaS infrastructure such as Amazon EC2, S3, Rightscale, vCloud. The next platform as a service (PaaS); the runtime environment for applications, development, and data processing platforms falls under the categories of PaaS like Azure, Google App Engine, and Aneka. The last software as a service (SaaS) deals with End-user and scientific applications like Flickr, Salesforce (Panwar et al., 2018). Rather than cloud computing attend to three basic models for the inauguration of infrastructure services such as Public, Private, and Hybrid Cloud. In public third party service providers managed the virtualized data center. In the Private cloud, the large organization deals with its infrastructure, and in case if more resources are needed it approaches the public cloud, which refers to the hybrid cloud (Banerjee, et al., 2015). The resources available in the data center are heterogeneously placed in different availability zone throughout the world interconnected by the web interface. These resources presented to the user in a virtualized manner. A key technology in cloud computing is virtualization in which a single physical unit of the resource act as multiple units and access by the different user which provided a less cost, scalable and efficient environment (Alworafi, et al., 2019). The most common is hardware virtualization, in which multiple virtual machines (VM) or instances are created for implementation and submission of user tasks. VM is an image of the host (Physical Machine) and the host has some hardware configuration shared among different VMs running on that host (Mapetu, et al., 2018). When the user increases correspondingly the huge amount of user task generated that may down the system performance.