Elegantly Balancing Speed, Simplicity & Risk:
Legacy Twin to Migrate Mainframe to Microsoft Cloud

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A consistent barrier to mainframe migrations to cloud is risk. Decision makers responsible for essential core systems are uncomfortable with any form of service disruption, much less one that could be avoided by maintaining the status quo. But what if mainframe applications and data could be moved to cloud and continue to be processed on the mainframe? This is precisely what Microsoft has been delivering for our more risk averse customers: simultaneous processing on mainframe and in cloud, enabling a safe, reliable, and controlled migration – on your terms.

For highly regulated industries, including banking, insurance, and healthcare, Microsoft's Legacy Twin pattern unlocks and de-risks the journey from mainframe to cloud. This proven approach offers decision-makers peace of mind, knowing that their core applications and data can co-exist in mainframe and cloud, with fully observable transactional integrity, and fallback capability. As an added benefit, this pattern is also now being used to introduce agility with Azure DevOps, whilst future-proofing with extensibility of the wider Microsoft Cloud platform.

So, what are the key principles of the Legacy Twin pattern?

The core tenets include: a single codebase that co-exists in mainframe and cloud; comprehensive automation to migrate applications and test for discrepancies between source and target with real production traffic; and migrate and replicate data migration for testing and fallback. Together, these principles ensure error free and performant applications in Azure, delivered through a roadmap of gradual application and data migration.

This tried and trusted formula is purposefully designed to minimize risk and support our most highly regulated customers across all industries. If your business remains bound to mainframe because of historical concerns about migration risk, or you’re seeking greater agility through incremental change, our Legacy Twin pattern may hold the key. Moreover, it ultimately lowers operating costs through the elimination or reduced consumption of mainframe services.

If you would like to learn more about Legacy Twin, and our experiences of successfully delivering these initiatives at scale, please contact us at mainframetransformed@microsoft.com.