Migrating your IBM mainframe to Amazon Web Services (AWS) can provide many benefits, including increased scalability, improved disaster recovery, and reduced costs. However, migrating a mainframe system can be complex and requires careful planning. This post will cover the key considerations and steps for moving your IBM mainframe to AWS, but first, you need to get an accurate lay of the environment you will be migrating.

Understanding Your IBM Mainframe Environment

There are several aspects to consider when understanding your IBM mainframe environment. To begin, you must identify the hardware and operating system your mainframe is running. This includes gathering information about the CPU type, memory, storage capacity, and other components such as tape drives or other peripherals. You should also determine which version of the operating system you are using and any patch levels that may be applied.

In addition to the hardware and operating system, it’s important to understand all the software that is currently installed on your mainframe. This includes applications such as databases, web servers, middleware, and more—all of which will need to be carefully denoted when migrating to AWS. Also, understanding any specific customizations that have been made to these applications is crucial to understand before considering migration. Some of your business-critical applications may not be suited for the cloud as-is and may require re-architecting before transferring off of your IBM mainframe.

Likewise, it’s important to understand the performance metrics of your current mainframe environment to select the right resources for migration. Understanding performance metrics means gathering data on factors such as workloads, usage statistics, peak hours of operation, and any other key metrics that could impact your migration strategy. Once this data has been collected, you can make better decisions about selecting the appropriate AWS resources for your new environment.

Planning Your AWS Migration

It is only after you have a thorough understanding of your current mainframe environment that you can begin planning a migration. This process involves creating a detailed plan that outlines the steps that need to be taken, the resources required, and the projected timeline for the migration. A key part of the planning process is identifying any challenges or risks that arise during the migration and creating a plan to mitigate them.

With your migration plan established, consider what resources you need to complete the migration successfully. This can include personnel with specific skill sets (such as DevOps engineers), hardware resources (such as servers or storage), software tools (such as cloud deployment platforms), and other assets (such as access control systems). Create a budget for these materials so you know what expenses need to be covered throughout the process. By engaging an AWS-specific staffing organization, such as NerdRabbit, you can find the talent you need at the budget you set. 

Planning an AWS Migration can be time intensive but is necessary for ensuring successful outcomes. Investing time upfront in planning can save time later on when encountering issues or delays during the actual migration process itself. Additionally, having a plan in place allows everyone involved in the project—from engineers to managers—to work together toward achieving common goals efficiently and effectively.

Choosing the Right AWS Services when Migrating

When it comes to migrating legacy mainframe applications to AWS, you need to consider how much time it might take to refactor to be compatible with cloud-native services. Refactoring also preserves business logic and optimizes the performance of your legacy application. Automated COBOL Refactoring is available for most COBOL dialects and platforms, including z/OS, OpenVMS, and VME.

After refactoring your applications, consider utilizing Amazon EC2. It is a popular choice for migrating IBM mainframes to the cloud because it provides the flexibility and scalability needed for running virtual machines in the cloud. With Amazon EC2, you can choose from several different operating systems and configure the virtual machine to meet your specific system requirements. You can also create multiple copies of your instances so that you have a backup ready if something goes wrong with one instance. Additionally, Amazon EC2 provides built-in security features to protect your data from unauthorized access as well as automated patching for eliminating vulnerabilities.

In addition to Amazon EC2, other AWS services may be used when migrating an IBM mainframe to the cloud. Amazon S3 is a great option for storing data since it offers high durability and scalability. Amazon EBS provides block-level storage and can be used to create permanent storage disks or snapshots that can be reused in cases of system failure. For more specialized IBM Mainframe storage needs, you can use Amazon’s Elastic Block Store for IBM z/OS (EBS for z/OS).

IBM Mainframe Data Migration

One of the most critical parts of migrating an IBM mainframe to AWS is migrating the data. This process can be complex and time-consuming, particularly if you have a large amount of data to migrate. If your IBM mainframe is hitting End of Service Life (EOSL), consider third-party maintenance services to extend the life of your mainframe at up to 50% less than IBM support services for the duration of your migration. It is more cost-effective to use third-party maintenance services when migrating off your mainframe and avoid expensive hardware upgrades that can be a drain on your project budget.

Data migration should be considered a separate step in the migration process, with its own resources and timelines. There are several tools available that can assist with data migration, including the AWS DataSync service, which allows you to copy data between different storage locations. The AWS DataSync service is an effective tool for managing data migrations between different locations. This tool allows you to quickly and easily copy large amounts of data between different storage locations with little effort needed from IT staff.

Furthermore, it can help automate some of the more tedious tasks associated with traditional methods such as file transfers via FTP or manual replication processes by allowing you to set up schedules for recurring synchronizations. AWS DataSync also provides other useful features such as compression algorithms and AES-256 encryption that help keep your data secure while transferring it over long distances across multiple networks. ReluTech offers Elastic Maintenance services billed through the AWS marketplace that keep your cloud-committed hardware online with support that mirrors that of IBM without sacrificing the quality of service. Data migration is typically the longest step of the migration journey and can be problematic if your mainframe loses its support from the OEM.

Testing and Validation for your Migration

When migrating to an AWS-based mainframe environment, it’s important to thoroughly test and validate the new system after the data has been migrated. This includes testing the performance of the system and any applications and customizations that are running on it. It’s also important to make sure all necessary data has been migrated correctly, as well as any associated dependencies or customizations.

To ensure a successful migration, it’s essential to perform several tests such as load testing, stress testing, and compatibility testing. Load testing checks how quickly the application will respond when multiple users are using it simultaneously. Stress testing examines how the system responds when subjected to extreme loads to ensure that it can handle peak loads without crashing or slowing down. Compatibility testing checks whether applications are compatible with each other or with different operating systems.

Other tests should also be done such as security tests to evaluate the security measures put in place by AWS and software audits that check for coding errors and vulnerabilities in applications running on the mainframe. Backup processes should be tested regularly so that there is an up-to-date backup of all data stored in case of an emergency.

Once these tests have been completed successfully, organizations should also consider conducting user acceptance tests (UAT) where actual end users are invited to provide feedback about their experience with the new system. This allows companies to identify potential issues before they become major problems down the road while ensuring a smooth transition from one platform to another for their users.

Operations and Maintenance

When operating and maintaining the new AWS-based mainframe environment, it is important to stay mindful of performance and cost concerns. This should be done through regular monitoring and evaluation of the system, as well as the implementation of updates and security patches. Monitoring performance should help identify any issues that arise, so they can be addressed quickly and effectively. Updates are important for keeping up with current trends in technology and ensuring that the system is secure against potential threats. Security patches are also critical for safeguarding the environment from any security vulnerabilities or exploits.

For cost optimization, it is also necessary to monitor system performance and review usage patterns. By identifying areas where resources can be better utilized or scaled back, organizations can ensure they get the most out of their mainframe environment while minimizing expenses associated with its operation and maintenance. Furthermore, this helps maintain a reliable platform for running business-critical applications or services.

For organizations looking to reduce costs further, cloud-native technologies such as serverless computing can also be used to help streamline operations by eliminating manual tasks associated with configuration management or deployment automation. Organizations can also use tools like auto-scaling to automatically scale resources up or down based on usage patterns in order to maximize cost savings.

Overall, operating and maintaining an AWS-based mainframe environment requires a proactive approach that ensures performance is consistent and any issues are addressed quickly. Regular monitoring of performance metrics along with periodic reviews of usage patterns can help optimize costs while also allowing organizations to take advantage of cloud-native technologies like serverless computing or auto-scaling when available.


Migrating an IBM mainframe to the AWS cloud can provide many benefits, including increased scalability, improved disaster recovery, and reduced costs. However, migrating a mainframe system can be complex and requires careful planning.

Researching all options carefully before deciding on a solution is critical before beginning your migration project. Consider factors like cost, the complexity of the migration process, security measures provided by each service or tool, and the overall requirements of your specific environment before deciding on which one best meets your company’s needs.

ReluTech offers a cost-effective solution for those looking to migrate their IBM mainframes to AWS. ReluTech can purchase legacy hardware upfront and then lease it back to you until the migration is complete – allowing you uninterrupted operations while saving money on upkeep costs and helping fund the migration services themself. Learn more about how you can save on migrating your legacy data to AWS by requesting a quote today.


Jason Figliolini is our Marketing Content Manager here at ReluTech. His top priorities are content creation for articles, blogs, and collateral to educate customers about cloud, hardware, and maintenance solutions. Outside of work, he enjoys reading books, attending concerts, and exploring Atlanta’s hidden gems.

Get in touch with Jason: jfigliolini@relutech.com