A cloud migration strategy is the high-level plan an organization adopts to move existing on-premises and/or co-located application workloads and their associated data into the cloud. Most plans include a public cloud migration strategy where the target is Amazon Web Services (AWS), Google Cloud Platform (GCP), Microsoft Azure, or other public cloud providers. Although most workloads will benefit from cloud migrations, not all workloads are suitable for migration.

A successful enterprise cloud migration strategy will include prioritizing workloads for migration, determining the correct migration plan for each individual workload, developing a pilot, testing, and adjusting the strategy based on the results of the pilot. A cloud migration strategy document should be created to guide teams through the process and facilitate roll-back if necessary.

Whether or not the source and destination platforms have similar architecture and use of migration tools that are fit-for-purpose will have a significant impact on the effort and cost of migration.

The desired final state is a seamless transition of the applications from on-premises to the desired cloud infrastructure without impacting application availability or day to day operations.

Adopting an cloud migration strategy helps identify and execute the fastest, lowest cost, least disruption transition from on-premises to cloud. And, can help determine which existing application workloads can be discontinued or replaced, which should be rewritten, which may remain on-premises, which should be moved as-is to a cloud platform to run as-is or targeted to be augmented with native cloud services, and which cloud is the right destination for which application. An enterprise cloud migration strategy will include a combination of these approaches to address the entire application portfolio.  

Since every organization is different, an enterprise cloud migration strategy should be tailored exactly to their particular needs and to achieve the desired business and technical outcomes. This requires knowledge of the business goals and the application portfolio that can provide visibility into the TCO and ROI of undertaking a migration.

1. Cost and time savings are a major benefit of a well-planned cloud migration.  Migration can take months or years if source and destination platforms are different. With consistent infrastructure and consistent operations, migrations can be automated, and workloads moved on masse without any downtime.
2. Many organizations undertake a cloud migration to support overall IT modernization efforts. Organizations that adopt a cloud-native approach utilizing micro-services and APIs naturally use cloud providers – frequently more than one – to deploy modern, containerized application workloads. Additionally, since cloud providers utilize the most modern servers and storage, organizations no longer need to plan for technology refresh, and can instead focus efforts on solving business problems without worrying about upgrading memory or OS in a server.
3. Instant scalability can be realized by migrating to public cloud providers, enabling enterprises to meet changing demand at will, whether fluctuations are caused by seasonality, business growth, or another spike. Cost savings can be considerable since resources are only paid for while in use.
4. Security can be improved by cloud migration strategy as well. Although most cloud providers utilize a shared responsibility model, cloud infrastructure is typically far greater than an organization’s own on-premises infrastructure was. Most cloud providers offer security analytics, block unwanted traffic, and ensure OS and security updates are applied with no action required by user organizations. Additionally, cloud-based applications and data are always available regardless of the status of end-user equipment. 
5. Accessibility is greatly enhanced by cloud migrations. Since applications and data can be accessed from virtually anywhere, employee productivity likewise improves since workers can access business-critical applications and data from home, while on the road, even while at the office exactly as they had in the past. Additionally, since business applications and data are now in the cloud, machine downtime does not cause loss of access and operations can continue virtually uninterrupted.

Additionally, access between applications can be greatly enhanced by a cloud migration. Cloud-native application methodologies promote the use of APIs to share information between applications and services regardless of where they reside. This approach not only provides a standard way for applications to communicate, it also improves access to information previously siloed into a single application. Now data can be shared among applications in a simple, predictable manner.

There are several options when considering workload migration.

• Relocating Perhaps the simplest form of migration, this strategy refers to moving VMware VMs from on-premises hardware to VMC. This can be achieved by reprovisioning from scratch, a cold migration, or a live migration.
  
• Reprovision from Scratch While this might not technically be considered a migration, it may be an option some of your cattle workloads. Instead of moving them, it might be possible to spin them up as new workloads in VMware Cloud on AWS instead. Simply bring them up as new in the cloud and turn the old ones off in you on-premises environment.
• Cold Migration The next migration strategy is a cold migration where a workload is stopped, moved over to your VMware Cloud on AWS and then restarted there. This option may work well for your non-production workloads where you can simply turn it off with minimal business impact (e.g. development or test workloads).
• Live Migration The ability to move a live running VM between your on-premises environment and your VMware Cloud on AWS SDDC is almost table stakes when talking about a hybrid cloud. vMotion can be leveraged with VMware Cloud on AWS.
• Replatforming This model modifies or replaces certain components to better take advantage of the cloud provider’s features, for example switching to managed services or replacing commercial off the shelf software with an open-source equivalent.
• Repurchasing Decommissions the existing application and replaces it with an already available cloud-based version from the cloud provider’s marketplace – in essence replacing one license fee with another. This approach is often utilized for older on-premises ERP, finance, CRM or HR applications which have equivalent functionality either in an app marketplace or as a SaaS application. This is also a good choice for legacy applications not easily virtualized or migrated in other ways.
• Refactoring This approach entails an entire re-architecting of an application to take advantage of unique cloud provider features. When cloud-native features are required or the agility and scalability of micro-services based applications calls for it, these applications are typically then broken up into smaller pieces or services and often deployed in a containerized environment on one or more public clouds. Although this is the most expensive approach to migration, the resulting benefits can far exceed the potential risks. Over time, many applications that were migrated with another strategy may become refactored as the increased benefits of cloud-native applications beckon.
• Retaining Not truly migration, this is retaining an application on its existing on-premises infrastructure. If there is still a strong investment, or if a critical application is running on legacy mainframe or minicomputer platforms, the organization may wish to keep those well-behaved and productive applications right where they are, using APIs to integrate with cloud-based resources. This results in a hybrid cloud migration strategy with workloads in public and private clouds.
• Retiring Every applications becomes obsolete, wither due to redundancy or the availability of better options in a cloud-based offering.