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5 Steps for Migrating Legacy Applications to the Cloud

Are you considering migrating legacy applications to the Cloud? Before you move forward, you need to create a clear plan to minimize downtime and ensure a successful migration. In this guide, we’ll walk you through 5 simple steps to successfully migrating legacy applications to the cloud, as well as highlight common mistakes and pitfalls that you might face. Feeling overwhelmed? No worries – skip the article and get in touch with a Mission Cloud expert for a free migration readiness assessment.

Why Should You Migrate to the Cloud? 

Legacy applications, while reliable, often lack the scalability, cost-efficiency, and performance required to meet modern demands. Migrating legacy applications to the cloud allows your company the ability to scale resources on-demand, optimize operational costs, and achieve enhanced application performance, allowing you to remain competitive. 

How to Migrate: 5 Steps for a Seamless Migration

1. Understand Your Current Environment

Because migrating applications to the cloud involves so many moving parts, the first step in a migration is gaining a thorough understanding of your current application architecture.  This deep understanding of your existing application architecture is the foundation upon which successful migrations are built; it mitigates the risk of encountering unexpected issues and disruptions and informs your choice of cloud services providers and migration processes. 

Here are some areas to consider as you evaluate your environment: 

  • Identify dependencies to ensure all necessary components are transferred to the new environment
  • Understand data compatibility issues, addressing potential disparities in data format or structure between the old and new systems.
  • Outline performance discrepancies to anticipate and address any differences in system performance that may arise during migration.
  • Understand integration complexities to ensure the seamless functioning of interconnected components in the new environment.

Consider employing tools like code analysis and profiling tools, along with techniques like impact analysis and dependency mapping, which can streamline the migration process and minimize risks. Balance your use of automated tools with manual code reviews to verify that the nuances of your particular environment are accounted for. 

  1. 2. Choose the Right Cloud Service Model:

When determining the appropriate cloud service model for migrating your applications, three primary options are available:

  • IaaS (Infrastructure as a Service): 

IaaS provides virtualized computing resources over the internet. It includes virtual machines, storage, and networking. Users have full control over the operating system and software stack, providing flexibility in infrastructure while outsourcing the hardware management. This makes IaaS ideal for migrating legacy applications that rely on specific configurations since migration requires minimal code changes.Consider IaaS when your migration project involves running virtual machines or hosting applications that require precise OS and middleware settings.

  • PaaS (Platform as a Service): 

PaaS offers a platform that includes infrastructure, runtime environment, and development tools. It abstracts much of the underlying infrastructure, focusing on application development and deployment.  It offers a platform equipped with tools and services that simplify the development processes — like application management, scaling, and updates —  allowing your team to focus on coding instead of infrastructure management. 

PaaS is preferred for migrating apps for development and deployment purposes, involving web development, APIs, mobile apps, or implementing continuous integration and continuous delivery (CI/CD) pipelines.

  • SaaS (Software as a Service): 

SaaS is the go-to option for straightforward applications with minimal customization needs. It’s used more frequently for new, cloud-native applications rather than migrating legacy applications, but it can be considered when modernizing certain components. 

With SaaS, users don't manage the infrastructure, they simply use the software. Maintenance overhead is reduced since users are able to just use the operating system, or software stack. This makes it an excellent choice when migrating applications such as email services (e.g., Gmail), productivity tools (e.g., Microsoft 365), or customer relationship management (CRM) solutions (e.g., Salesforce). It's particularly valuable for applications that serve specific business functions.

Beyond the technical requirements of migrating legacy applications to the cloud, you should also consider these things when choosing the right cloud service provider.

  • Application Complexity: Assess the complexity of your application. IaaS suits highly customized and complex applications, while simpler, standardized ones may work well with PaaS or SaaS.
  • Scalability: Consider the potential for growth during migration. IaaS offers more control over scaling, while PaaS and SaaS often provide automated scaling options.
  • Budget: Evaluate the cost implications of each model. IaaS may require more management but can be cost-effective for certain workloads, while SaaS often has predictable subscription fees.
  • Security and Compliance: Depending on your industry and regulatory requirements, one model may offer better security and compliance features than others. Ensure compliance during migration.
  • Development Expertise: The expertise of your team can influence your choice. SaaS requires minimal expertise, while IaaS may demand more infrastructure management knowledge. Consider your team's capabilities during migration planning.
  1. 3. Selecting the Right Cloud Provider:

When it comes to choosing a cloud provider for your applications, it's essential to consider the strengths and expertise each major player brings to the table. Amazon Web Services (AWS), Microsoft Azure, and Google Cloud are three of the most prominent cloud providers, each offering unique advantages. In this section, we'll delve into their strengths and areas of expertise to help you make an informed decision during your cloud provider selection process.

Amazon Web Services (AWS):

  • Broad Service Offering: AWS boasts an extensive range of services, covering everything from computing and storage to advanced technologies like machine learning and the Internet of Things (IoT). This breadth makes it a versatile choice suitable for a wide array of application needs.
  • Global Reach: AWS maintains a global network of data centers strategically positioned around the world. This extensive network ensures low-latency access for users and data redundancy, contributing to high availability.
  • Extensive Ecosystem: AWS has cultivated a robust ecosystem of partners, tools, and third-party integrations. This ecosystem enhances flexibility and provides access to a wide array of resources for optimizing your cloud environment.
  • Expertise: AWS is renowned for its extensive experience in hosting diverse types of applications, including legacy systems. It offers a mature set of migration tools and resources, simplifying the process of moving your applications to the cloud.

Microsoft Azure:

  • Integration with Microsoft Products: Azure seamlessly integrates with Microsoft software and services, making it an attractive option for organizations heavily reliant on Microsoft technologies. This integration simplifies the management of existing assets and workflows.
  • Hybrid Cloud Capabilities: Azure excels in hybrid cloud scenarios, allowing organizations to seamlessly integrate on-premises infrastructure with cloud resources. This makes it a preferred choice for businesses with existing on-premises investments.
  • Enterprise Focus: Azure offers comprehensive enterprise-level services, including robust support for artificial intelligence (AI), analytics, and identity management. This comprehensive suite of offerings caters to the needs of large organizations.
  • Expertise: Microsoft Azure is often the preferred choice for enterprises looking to migrate Windows-based legacy applications. Azure provides robust Windows support and tooling, making it well-suited for organizations with a significant Windows footprint.

Google Cloud:

  • Data and Analytics: Google Cloud is renowned for its data analytics and machine learning capabilities. It excels in handling data-intensive applications and provides powerful tools for data processing and analysis.
  • Containerization: Google Cloud offers strong support for containerization and Kubernetes orchestration. This appeals to organizations embracing containerized applications, as it simplifies container management and scaling.
  • Innovation: Google Cloud is recognized for its innovation in artificial intelligence and cloud-native technologies. It consistently introduces cutting-edge solutions, making it an attractive option for forward-thinking companies.
  • Expertise: Google Cloud is an excellent choice for organizations with a focus on data analytics and machine learning. It is often preferred by startups and tech-driven companies looking to leverage Google's expertise in data and AI technologies.

In conclusion, each major cloud provider, whether it's AWS, Microsoft Azure, or Google Cloud, comes with its own set of strengths and expertise. Your choice should align with your specific application needs, existing technology stack, and long-term business goals. By carefully evaluating these strengths and expertise, you can make an informed decision that maximizes the benefits of cloud computing for your organization.

  1. 4. Plan the Migration Strategy:

  • Discuss the importance of creating a detailed migration plan.
  • Explain the different migration strategies (Rehost, Refactor, Rearchitect, Rebuild, Replace) and when to use each.
  • Provide a step-by-step breakdown of the migration process.
  1. 5. Implementing the Migration:

  • Detail the actual migration process, including data migration, testing, and deployment.
  • Highlight best practices for minimizing downtime and ensuring a smooth transition.
  • Discuss post-migration tasks, monitoring, and optimization.

After you’ve created a robust, in-depth strategy for migrating legacy applications to the cloud, review your migration plan using the following checklist to help ensure you’ve covered major migration pitfalls:

  • Security: Is Your Data Safe in the Cloud?

It is important to choose a verified Cloud Service Provider before you surrender control of your intellectual property in order to prevent your company from being on the wrong side of litigation. Preparation for security concerns should be undertaken at the beginning of any cloud strategy to ensure that the company’s data is secure. For Example: Amazon Web Services is a verified Cloud service provider and utilizes best practices to secure the users data in AWS Cloud. Learn more at AWS Security Best Practices.

  • Disaster Recovery: What is Your Backup Strategy?

 If your cloud computing system experiences downtime or is faced with a disaster, how is your Cloud Service Provider going to get you out of the crisis? To ensure business continuity, it is vital for employees and clients to still have the ability to access company data. For any amount of downtime, businesses should have some knowledge of what constitutes an outage and when fiscal penalties should take effect. Learn more at AWS Disaster Recovery.

  • Scalability: Can Your Application Scale with Your Company? 

There is a limitation to everything. A cloud application is scalable, with a “pay as you go” strategy based on demand but even the Cloud has constraints. While framing a Cloud strategy, focus on the various “ceilings” like organization, storage, people, technology and cost to determine how much and how far your application is scalable. Determining your existing software compatibility with the Cloud is highly crucial as well. Learn more at AWS Auto Scaling.

  • Reliability: Can You Depend on Your Cloud Services Provider for Consistent Service? 

It is important to determine your vendor’s margin of error, frequency of power outages and security issues. Also, keeping a check on the accessibility and availability of cloud services can help you decide the best suitable cloud service provider for your business.

Whether you need additional support in preparing your migration plan, or want an expert review of your completed plan, Mission Cloud is here to help. As an AWS Migrations Competency Partner, we offer a free 60-minute migration assessment to help you prepare for migrating legacy applications to the cloud on AWS. Get in touch with an expert and prepare for a successful migration to the cloud.



  1. How can one ensure that the migrated applications are fully optimized to leverage cloud-native features post-migration?

Ensuring that migrated applications are optimized for the cloud involves a thorough assessment pre-migration, followed by iterative refinements post-migration to exploit cloud-native features. This may include re-architecting the application to be more modular, implementing microservices, or integrating cloud-specific services for enhanced performance and scalability.

  1. What specific strategies or tools does Mission Cloud recommend for monitoring the performance of applications once they are migrated to the cloud?

For monitoring post-migration performance, adopting a comprehensive suite of cloud-native monitoring and management tools is crucial. These tools should offer real-time analytics, performance metrics, and the ability to quickly pinpoint and resolve issues to maintain optimal application performance in the cloud environment.

  1. Are there detailed case studies available that demonstrate the before-and-after impact of legacy application migration on business operations and efficiency?
  2. Definitely. These case studies can describe the before and after of migrating legacy applications to the cloud.

  3. 1. Intruity Leverages Mission to Migrate to AWS and Improve Application Performance
  4. 2. How the Boston Celtics Modernized Sports Analytics on AWS
  5. 3. 20% Improved Application Performance and Reduced AWS Migrations Costs by 70%


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