The necessity to implement the cloud based technology and infrastructure are growing rapidly for the last few years. Now days almost each and every establishment is in a desideratum of having any of the cloud based services. Usage of the internet makes the public and companies to think of storing data in the internet which makes the data access easier and more secure. The companies which runs the most of their hardware and software resources, Applications, Services, Workloads etc uses the data centre on their own campus . There is a lot of cloud service providers which helps to set off and wield data stored in cloud Company. Most of the Company expenses like operational expenses and capital expenses can be reduced with the usage of cloud migration which is fully on Pay As You Go billing model. In this paper we describe more about the cloud computing and its types, cloud migration services, benefits, strategy etc. More over this paper gives you a clear idea about cloud migration issues and challenges.
In this section, a brief survey about cloud migration and various cloud migration techniques and benefits were discussed Many authors give some useful information about cloud migration ,steps for migrating an application from existing system to cloud environment, secured data migration, legacy system migration to cloud environment, algorithm to combine the resources, load balancing and its techniques, live migration etc. Some of the useful works are explained below.
Ashish et.al proposed  a detailed view about cloud migration and its techniques. The authors briefly explained about the benefits of cloud migration, types of services needed for migration and various issues related to migration. Most detailed study of procedure or steps taken to migrate an application from an organization to cloud is neatly explained by the author. Some important points. The basic things needed while migrating to cloud environment is explained by the author. Those who are interested to know about the basic about cloud migration can get useful ideas from this paper.
Rithves.R et.al proposed  a detailed survey about various migration types and its phases. The author also explains about various security issues occur during migration. Paper clearly explains that the security given to cloud services were different. For example, In SaaS the attacks will be maximum in browsers. Because user donâ€™t know about the backend infrastructure. The user will simply use the different services using browsers. In PaaS, the application and data will be completely oversee and utilized by the user. Itâ€™s the duty of the service provider to manage the infrastructure. In IaaS the application, data and OS will be managed by the user. The service provider will maintain the infrastructure. The author also stated that in VM migration the passive and active attack will be high when it moves from one host to another.
Prasanth pant et.al  clearly explained that for a successful migration from basic infrastructure to cloud needs a intermediator or a middleware. Here the cloud integration tool can be said as an intermediator. This cloud integration tool reduce the gap between the the merchant and consumer. It is clearly explained that if the data is stored remotely in different areas and also managed by some organizations then some basic IT issues like privacy, integrity, security etc can be easily solved.
Awatef Balobaid et.al  gives an idea about cloud migration techniques and some limitations in cloud migration methods. It clearly said that there is a lack of security to fulfill a good live virtual migration technique. This paper clearly gives an idea about existing migration techniques.
Mehreen Ansar et.al  mainly focused on secure data migration. This paper clearly explained about giving security for migration with the help of Attunity . With the Attuniy the data transferring can be more simple and faster. A detailed comparison of cloud migration tools and cloud vendors are given in this paper. Risk in data migration is also explained with some solutions. The author stated that cloud to cloud data transfer is more efficient and secure migration process. Here before uploading data to the cloud,the data is encrypted using BCP encryption
Jun-Feng Zhao et.al  proposed a clear view about the legacy system migration to the cloud. The different tasks can be classified based on different cloud strategy. The author explained about Migration to IaaS, Migration to PaaS and migration to SaaS. Here the migration is classified in to five categories. Some future work like Holistic methodology, redesign and adaption were identified .it is clearly stated that with the help of REMICS the migration from legacy system to cloud will be performed in future.
Muhammad Ehsan Rana et.al  explains about the issues related to legacy systems from migrating to cloud environment. Different migration techniques like Hybrid migration, phased migration, Big bang migration, Fork lift migration were explained briefly by the author. Since it is less complex the fork lift migration is commonly used so that one period of down time for data migration. Cloud adoption model also explained here because of its detailed procedures for migrating data.
Feng D, et.al  proposed novel migration algorithm so as to consolidated the resources using a two level algorithm. Based on factors like CPU and Memory the hotspots are determine with the help of grey relational analysis (GRA) and some techniques for order preference. After that to reduce the energy consumption the resources are consolidated with the help of two- level heuristic algorithm. With the help of GRA and TOPSIS method, the hotspots are determined. The author clearly states that the proposed system migrates the VM quickly using PSO algorithm. The proposed ACO algorithm reduces the cost and power consumption.
Shahbaz Afzal et.al  explained about various load balancing techniques. Author points out various limitations and advantages of some existing methods in a clear way and give some ideas to develop a new efficient load balancing algorithm in future. A detailed comparative study on load balancing techniques was discussed by the authors. This paper recommends a new perceptivity which en route for load balancing in cloud computing.In order to recommend more efficient load balancing algorithm at later years , the challenges and issues of load balancing algorithm is explained here in detail.
TianZhang He et.al  the authors identify some parameters, which affect the live migration performance in openstack environment.The parameters may be system and network based parameters. Some affected performances are statis adjustment algorithm,comparison between parallel and sequential algorithm etc. Based on the QoS View,client and server response time is evaluated. Some importance parameters like Migration time, Down time, Transferred time were used to evaluate the performance of live migration in SDN-enabled cloud computing.A mathematical model of live migration in open stack is explained in this paper.
Shikha Singh et.al  clearly explained about the upcoming cloud application cloud product lifecycle management (PLM) and its challenges. The challenges which are found out are helpful for other companies having same issues before migrating to Cloud PLM. To explore the different demanding factor and their correlations, techniques like grey DEMATEL and ISM were utilized. In order to predict the relevant relationships grey DEMATEL is used. TO find out the hierarchy of the factors ISM is used. This paper clearly explain that for migrating to cloud PLM the most critical challenges were the data security and trust on solution provider. These findings may be helpful for the managers in different firms who like to shift to cloud PLM.
Maja Vukovic et.al  proposed an automated system for cloud migration. In order to assemble migration plans which are fully depended on some properties of source and target environments and with some migrating tools, a Metric-FF Artificial Intelligence is used. Here the author discuss about various challenges in migration. To provide large scale parallelism, s service â€“based system which employs BPM technology is used. During migration, the complexity will be increased. In order to handle it an Artificial intelligence planner is embedded to dynamically generate migration workflows.
Pooyan Jamshid et.al  proposed Variability â€“based pattern driven Architecture Migration (V-PAM).The V-PAM is based on heuristic confirmation from several migration process.With the help of V-PAM an organization can easily select migration pattern, combine them to form a migration plan, augment them based on new patterns.Almost all migration patterns are reusable and composable which can be seen as a building blocks. Microservices is said as a emerging cloud architecture which give more importance to servitisation and provide framework to support DevOps.In the development of different migration pattern the main role played is Automation
Mahdi Fahmideh Gholami et.al  proposed a legacy to cloud process model so as to explained the organizational legacy system which is reengineered for cloud utilization. The main aim is to point out the difficulties in migration of legacy systems to cloud . A Setof common activity were derived so as to express it as a modeland can be easily validated with the help of the 104 shortlisted domain experts from different sectors. With the help of SPSS Sample T-Test , the data are collected and analysed using a Web- based survey questionnaire. Based on these studies a practical guide is taken to conduct the transition. Main limitation about this model is generalisability.
Pieter-Jan Maenhaut et.al  set out the various steps needed to migrate existing application to cloud environment. And also explained about the steps needed to add multi-tenancy. Two case studies are carried out here so as to verify it for hospital based needs. During the migration these two case studies have to face lot of security and performance issues .Here the author proposed a system to migrate legacy software to the public cloud. The advantages of cloud migration and multi-tenancy are explained here in brief.
Olaf Zimmermann et.al  proposed a task-centric view architectural refactoring template which is mainly used to focus on the architectural decision. Here the quality stories helps for deriving architectural smell. Some common architectural refactoring is proposed here. Based on the project experience and cloud pattern literature the refactoring is compiled. De-SQL, Cache, Move responsibility can be said as the best examples for architectural refactoring. This paper mainly look for making the legacy system fully fit for the cloud environment after refactoring.
Martyn Ellison et.al  proposes a two stage method which will help to find out the cost estimation, duration needed for proper migration and cost for databases. At first the database workload and structure is migrate from database logs and database schema. Next the cost and estimates are obtained with the help of discrete event simulation. Here some software tools are implemented to make the system automated. The tools like DBLModeller and MigSim are used to make the migration faster. The system is evaluated by the author with the above said tools.
Anita Choudhary et.al  proposed a survey on live migration and various methods were analyzed.Here the type of migration and its techniques are classified .The various performance like cost, memory.migration time and data transferred were discussed. The author explained about various threats in live migration and divide them into different category. Various challenges in improving the performance of live migration were identified.
In this paper we discussed the usage of cloud computing and the benefits of organizations by using the cloud environment. The usage of cloud service models like IaaS, PaaS, SaaS were explained. Various cloud deployment model with their uses is briefly defined. Almost all organizations were improving their environment to cloud environment. The companies are migrating to cloud environment to get more benefited. Migration to cloud from an existing system is called cloud migration. Applications, OS , database can be migrated to cloud environment. The paper clearly explained the cloud migration and its benefits. Detailed about various cloud migration companies is explained with their services and location. Cloud migration strategies are explained here so as migrating the application, OS and database to cloud. A technique called virtualization is used to move the workloads from one environment to another. Usually, they are of live migration and cold migration. They are differentiated based on the VM status. A detailed literature survey is taken to show the cloud migration techniques, load balancing, security to cloud migration, legacy system migration , live migration etc.
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