Businesses are increasingly adopting digital transformation initiatives related to infrastructure, data, and applications. Cloud migration plays a critical role in these processes.
Put simply, cloud migration means moving all or part of your company’s business data, processes, operations, and applications into the cloud. This usually means transferring data, workloads and services to the cloud by recreating vital infrastructure elements utilizing cloud platform capabilities. The benefits are clear:
- Decreased hosting, compute, database, networking, and administration costs: In the cloud, you no longer have to keep your own physical servers running. On top of that, you no longer need to have a huge team of professionals supporting your on-premise infrastructure.
- Agility and scalability: Cloud-based services can scale to cope with fluctuations in user demand, while your teams can collaborate on projects and maintenance from anywhere.
- Disaster recovery: Cloud-based backup and recovery are more efficient, better maintained, and updated more regularly, making your operations more robust.
- Improved security: The cloud provider of your choice will take on a huge part of the security responsibility that was previously on your side, like the security of your infrastructure. It’s called the ‘shared responsibility model’.
- Reduced carbon footprint: Using aggregated cloud computing resources helps to reduce carbon dioxide usage, eliminating 1 billion tons of carbon emissions by 2024, as reported by the IDC.
But, the concept of cloud migration hides a significant amount of granularity. Not only can you carry out your migration in stages and at different levels, but you also need to optimize your cloud use. Get your strategy right and you’re winning, but get it wrong and you have a budget problem. It’s no wonder that Flexera’s 2021 State of the Cloud report revealed that while cloud migration is increasing, cloud spending and efficiency are a major concern for most decision-makers.
That efficiency begins at the start, with your migration plan. This article will explore the different cloud migration types and their pros and cons in order to give you a running start when considering your options.
A quick overview of application migration approaches
The choice of the approach to cloud migration can vary quite substantially in different organizations and businesses. The decision on how to handle the migration in your organization, first of all, will depend on your business’ motivations and objectives. Knowing precisely what you want to achieve with cloud migration is the first step towards building a specific and detailed path to fulfill it.
Above that, the approach to cloud migration depends on what your current on-premise infrastructure looks like. After a thorough audit of the current applications’ architecture issues, gaps and risks, it becomes quite clear which of your applications need to be retired/retained and which need to go through a migration phase. Both components, cloud migration goals and infrastructure state, will shape the cloud migration strategy for your business.
After you’ve clearly outlined your cloud migration goals and assessed your current as-is architecture, you can define your cloud strategy on your own or get expert help from cloud partners, like Avenga.
The most common cloud migration approaches are described here, ordered by the complexity and corresponding level of investment and expertise required. Each of the approaches has its advantages and disadvantages, and understanding what to expect from each approach can help you adjust your migration strategy more specifically to your needs.
Rehost: Rehosting is often called “lift and shift” because you move an entire application from your internal servers and place it in the cloud without any changes.
Replatform: Your applications and data are migrated to a cloud platform, utilizing some of the PaaS services of the cloud platform (e.g., managed data stores or messaging middleware). The overall system architecture will remain the same.
Repurchase: In this type of migration, a new SaaS solution replaces the existing one.
Refactor: Using this approach, you partially or fully redesign and optimize an existing application to improve performance and reduce costs.
Re-architect: This type of migration takes refactoring to the next level. It includes an architectural redesign that takes advantage of both multi-cloud and native cloud environments.
Rebuild: This involves redeveloping an app or solution from scratch, entirely in the cloud, while taking advantage of the latest tools and frameworks.
Retire: Sometimes, a cloud migration plan will reveal which applications can be discontinued. Retiring an application requires data to be archived and cleaned up. An application can also be withdrawn when part of its functionality gets refactored, re-architected, rebuilt, or repurchased.
The pros and cons of different cloud migration approaches
Different cloud migration approaches have advantages and disadvantages, and understanding what to expect from each type can help you adjust your migration strategy to your unique needs.
The rehost (lift and shift) approach
At this level of migration, your applications, data, and servers are moved to the IaaS tier of the cloud platform without major alterations. As a result, you continue to deal with servers, networking and per-server maintenance, only utilizing virtual machines and networking services of the cloud provider. Except, you don’t take full advantage of the capabilities of the cloud. If you have an application located on a traditional server, you lift it along with all the necessary runtimes and software. You can either virtualize the bare-metal environment or migrate the existing virtual environment and then install the app within a virtual server, like Amazon EC2 or Azure Virtual Machine, and deploy the application within that.
Advantages: Rehosting is the cheapest and easiest way to migrate to the cloud. It requires minimum time and expertise, and mitigates the risk of breaking anything by messing with your application’s code.
Disadvantages: Although rehosting is a comparatively simple approach, failures due to complex application dependencies or long outage periods might occur. If a virtual server goes down, your application goes down, similar to traditional server behavior. Additionally, even if a rehost cloud migration succeeds, you won’t be taking advantage of all the powerful cloud-native capabilities.
→ Read more about lift and shift…
The replatform approach
With replatforming, you migrate the application from a traditional server, make configuration and environment-specific changes, such as containerization of the service, state offload and distribution, session-management layer re-engineering, etc., and then migrate it to the cloud without modifying the application itself.
For example, say you have a legacy application running on a traditional server. You can replatform and utilize the advantages of the new cloud PaaS infrastructure. And, cloud architects can modify the way an application interacts with a database so it can take advantage of automation opportunities and a more varied database infrastructure.
In case you are moving an on-premises SQL database to a cloud-managed database, like AWS RDS (Relational Database Service), it may require a small number of changes that are usually limited to the application’s configuration. However, the wins are significant: the reduction of the operational burden, out-of-the-box mirroring and fault-tolerance, as well as other benefits.
Advantages: Replatforming doesn’t require a massive investment in time or money and several SaaS options provide replatforming solutions. The replatform approach allows you to improve a part of an application while the rest of the application remains operational in the cloud.
Disadvantages: Replatforming applications can sometimes get out of hand. It can vary from deploying just a few small changes to the application or service, up to a complete re-architecture of some components. Hence, replatforming might involve risks, such as errors in the code or configuration. You need to establish a thorough plan of which features you want to change beforehand and those changes should be very carefully implemented.
The repurchase approach
Repurchase means moving from purchased on-premise software to a cloud-based SaaS equivalent. For instance, transferring from CRM to Salesforce, or transfering the backend code that was hosted on premises to the private cloud data server.
Repurchasing software is a good option if you want to harness the scalability, flexibility and agility capabilities offered by cloud solutions.
→ Find out more about ready-made solutions from Avenga
Advantages: Since the product you use is already configured for the cloud, you don’t need to spend time and effort configuring it yourself. More importantly, repurchasing can be cheaper than refactoring, as we’ll see next.
Disadvantages: Sometimes the repurchase approach can be more expensive than hosting the app or service on your own premises. It also requires a high-speed bandwidth connection and a poor connection can be the cause of potential downtimes. What’s more, if your application is highly specialized and has unique features, repurchasing won’t be a viable option.
The refactor approach
Refactoring means re-engineering your application to become a cloud-native. For instance, you could migrate existing applications to virtual services or refactor relational and nonrelational databases into Amazon Aurora and Azure Cosmos DB.
The need to refactor is often induced by a business’ necessity that requires the need to add new functionalities and/or to easily scale up and down, which would be hardly achievable with the current service’s architecture.
Advantages: Refactored applications take advantage of cloud-native capabilities. From the long-term perspective, refactored software is much more cost-effective than a non-refactored app. They are quick, reusable, and allow on-demand provisioning.
Disadvantages: Refactoring has high initial costs and is time-consuming compared to other approaches.
The re-architect approach
Re-architecting optimizes an application and makes it more scalable, secure, accessible, fast and agile by modifying and extending its functionality. Such as, you could separate a monolithic application into many independent microservices that can be read, written, and executed independently.
Advantages: While the refactoring approach involves restructuring the code, the re-architect approach is about changing the way the code is functioning, thus capturing the value of the business advantages that are independent of the legacy codebase. Basically, re-architecting is refactoring at a higher level. Re-architecting means moving the service into a fresh paradigm, in the meantime reducing the specific parts of code.
Disadvantages: Re-architecting is even more time-consuming than refactoring and requires a higher amount of initial effort. The code re-architecting may be complicated to carry out, which can potentially lead to bugs or security issues as the changes will be deployed to production.
The rebuild approach
With rebuilding, you create your application directly in the cloud, taking advantage of all the tools available. The rebuild approach is often used when the new changes in the app require the code to be rewritten. In some cases it may be more challenging to read the old code than to build it from zero.
Advantages: Building an application from the ground up will enable you to fully utilize everything the cloud has to offer. It is much easier to support and widen the app or service, when it is built in the cloud from scratch.
Disadvantages: It takes time and effort to get a new application off the ground. Rebuilding the app or service in the cloud may potentially introduce new bugs that developers haven’t encountered in the legacy app.
The retire or retain approach
When you plan to migrate to the cloud, you may find that some applications are no longer necessary for your business and don’t need to be included in your migration plan. Alternatively, there may be applications that you use but don’t want to include in your migration for various reasons. The retire approach is used when the application or service is used infrequently or sporadically, and it’s not worth being rehosted, replatformed, or re-architected to the cloud. In this case, the app can be retained on the local servers.
Advantages: The retiring approach helps you free up space on your on-premises servers, clear out your infrastructure, and eventually reduce costs. Additionally, retiring obsolete business applications can deliver significant cost savings, as substantial amounts of software budgets are spent on app maintenance.
Disadvantages: If an application’s maintenance and support costs are much higher than the usefulness it brings and you’ve decided to retire it, then it might require energy and effort to build a useful app from scratch.
After checking out the advantages and disadvantages of each approach, it is time you have a look at the collection of products and services that the top cloud providers recommend for the migration, in terms of the specific approaches your company would like to pursue.
Here you can find a comparison of the top cloud data migration service providers, including AWS, Azure, and Google Cloud.
What are the 7 types of cloud migration? ›
A migration plan often consists of several strategies, each used to handle a different component of the existing IT architecture. There are seven cloud migration strategies: rehosting, redeployment, repackaging, refactoring, repurchasing, retiring, and retaining.What are the 5 cloud migration strategies? ›
- Rehost. Rehosting, or 'lift and shift,' involves using infrastructure-as-a-service (IaaS). ...
- Refactor. Refactoring, or 'lift, tinker, and shift,' is when you tweak and optimize your applications for the cloud. ...
- Revise. ...
- Rebuild. ...
The 4Rs of Application Cloud Migration, essentially Rehosting, Refactoring, Re-platforming, and Replacing, allow enterprises to draw out a plan for migrating their applications to Cloud.What are 3 major cloud types? ›
From his Essay of the Modifications of Clouds (1803) Luke Howard divided clouds into three categories; cirrus, cumulus and stratus. The Latin word 'cirro' means curl of hair. Composed of ice crystals, cirro-form clouds are whitish and hair-like.What are the 3 main phases to a cloud migration? ›
The following sections discuss each phase in detail: Phase 1: Prepare. Phase 2: Plan. Phase 3: Migrate.What are the 6 strategies for cloud migration? ›
Collectively known as the “6Rs of migration,” the migration process involves, Retiring, Retaining, Rehosting, Replatforming, Refactoring, and Re-architecting.What are the three approaches to cloud migration? ›
These three approaches are lift and shift, application refactoring, and re-platforming –each of which we'll get into, discussing their purpose and migration process.What are 4 types of migration? ›
internal migration: moving within a state, country, or continent. external migration: moving to a different state, country, or continent. emigration: leaving one country to move to another. immigration: moving into a new country.What are the 9 types of migration? ›
- Internal migration: moving within a state, country, or continent.
- External migration: moving to a different state, country, or continent.
- Emigration: leaving one place to move to another.
- Immigration: moving into a new place.
- Return migration: moving back to where you came from.
- Chain Migration. ...
- Cyclical Migration. ...
- Economic Migration. ...
- Environmental Migration. ...
- External Migration. ...
- Forced Migration. ...
- Internal Migration. ...
- Interregional Migration.
What is the most common cloud migration model? ›
Rehost or lift-and-shift model
Rehosting is the most straightforward cloud migration path. It means that you lift applications, virtual machines, and server operating systems from the current hosting environment to public cloud infrastructure without any changes.
Prerequisites For Cloud Migration
There are various advantages in such a cloud migration process and they are: a) scalability, b) powerful computing capabilities, c) flexibility, d) no issues in server maintenance, e) storage capacity, f) cost-as-go and g) performance.
However, to fully leverage the power of AWS resources, you need to pre-design your migration process. This article explains how to design a five phase AWS migration process that includes migration preparation, discovery and planning, designing, migrating, and validating applications, and managing operations.What are 7 notes in cloud migration planning? ›
What is this? To summarize, these are the cloud migration strategies also known as the 7Rs. They are retain, retire, relocate, rehost, replatform, repurchase, and refactor.What are the 6r principles cloud? ›
However, we at Txture still rely on the 6 key strategies of Orban's article: Rehosting, Replatforming, Repurchasing, Re-architecting, Retire and Retain.What are the 4 primary cloud names? ›
The different types of clouds are cumulus, cirrus, stratus and nimbus.What are the 11 more major categories in cloud computing? ›
Names for clouds
- Stratus/strato: flat/layered and smooth.
- Cumulus/cumulo: heaped up/puffy, like cauliflower.
- Cirrus/cirro: high up/wispy.
- Alto: medium level.
- Nimbus/Nimbo: rain-bearing cloud.
- Storage Migration. If you've ever transferred business data from disks to the cloud, you've done a storage migration. ...
- Database Migration. ...
- Application Migration. ...
- Business Process Migration.
- 7 steps of Cloud.
- Application discovery and assessment. ...
- Establishing the platform. ...
- Implementing security controls. ...
- Application migration. ...
- Assurance. ...
- Governance & PMO.
What are the main factors for cloud migration? ›
- Factor #1. Migration Goals.
- Factor #2. Infrastructure Changes and Performance.
- Factor #4. Compatibility & Cost.
People migrate within their countries for many reasons. The causes can be divided into five categories: cultural, demographic, environmental, economic, and political causes.What are the 5 stages of migration? ›
There are five common migration approaches: Retire, Replace, Rehost, Rearchitect, and Retain.What are the 7 factors of migration? ›
These represent the various reasons why people migrated to and from Britain; or they represent the reasons why the British Empire developed or decline.
- ❖ War. ...
- ❖ Religion. ...
- ❖ Government. ...
- ❖ Economic resources. ...
- ❖ Science and technology. ...
- ❖ Ideas, or ideologies.
The movement often occurs over long distances and from one country to another (external migration), but internal migration (within a single country) is also possible; indeed, this is the dominant form of human migration globally.What are the top 5 causes of migration? ›
Some people move in search of work or economic opportunities, to join family, or to study. Others move to escape conflict, persecution, terrorism, or human rights violations. Still others move in response to the adverse effects of climate change, natural disasters, or other environmental factors.How many types of data migration are there? ›
In this case, we discover four types of data migration: database, application, storage, and cloud migration.What are three advantages and three disadvantages of the cloud? ›
- Advantage #1: Disaster Recovery (DR) ...
- Advantage #2: Access your data anywhere. ...
- Advantage #3: Low cost. ...
- Advantage #4: Scalability. ...
- Advantage #5: Security. ...
- Disadvantage #1: Lack of total control. ...
- Disadvantage #2: Difficult to migrate. ...
- Disadvantage #3: Requires Internet.
Security Risks: In addition to potential productivity impacts, an organization's move through intermediate states of cloud migration may carry security risks as well. If security policies and solutions are not updated in sync with cloud migration, corporate data and applications may be exposed to attack.What are the 6 phases of cloud migration? ›
The 6 Rs of cloud migration—re-host, re-platform, repurchase, retain, retire, and re-factor—can help you to determine clear paths for your migration. You can look at each “R” as a separate migration strategy.
What are the 6 R's of cloud migration? ›
Amazon Web Services (AWS) adopted this model and extended it to the 6 R's: Re-host, Re-platform, Re-factor/Re-architect, Re-purchase, Retire and Retain. This post covers the basics for each of these and explains how to decide which AWS migration strategy to choose for your applications.What are the four 4 deployment models cloud? ›
There are four cloud deployment models: public, private, community, and hybrid. Each deployment model is defined according to where the infrastructure for the environment is located.What are the 3 major emerging cloud deployment models? ›
- IaaS (Infrastructure as a Service) ...
- PaaS (Platform as a Service) ...
- SaaS (Software as a Service)
There are multiple cloud adoption strategies to choose from, but I want to simplify one adoption strategy into four steps: assess, plan, adopt and optimize. This analysis will provide definitive guidance for evaluating the pros and cons.How many phases are there in cloud migration? ›
Once the decision has been made that cloud is the best option to solve the business challenges you face (and it may not be), there are three phases of moving to the cloud: planning, mid-shift, and go-live.What are the challenges faced during cloud migration? ›
One of the key obstacles to cloud migration is data security and compliance. Moving data to the cloud presents security risks. Transferring large volumes of potentially sensitive data and configuring access controls for applications across multiple environments can expose your assets to cyber threats.