What is Rehosting?

Rehosting is an approach to migrating business applications hosted on-premises in data center environments to the cloud by moving the application “as-is,” with little to no changes to the functionality. A common rehosting scenario is the migration of applications that were initially developed for an on-premises environment to take advantage of cloud computing benefits. These benefits may include increased availability, faster networking speeds, reduced technical debt, and a pay-per-use cost structure.

In our experience, rehosting is well suited for organizations under time-sensitive data center evacuation mandates, facing pressure from leadership to migrate, running COTS software that doesn’t support modernization, or those with business-critical applications on end-of-support technologies. These organizations often opt for a rehost then transform strategy, as reviewed in the following blog, Cloud Transformation Can Wait… Get Me to the Cloud Now!

Below we outline important considerations, benefits, and challenges associated with a rehost strategy, based on our real-world experiences moving both custom and packaged commercial on-premises applications to the cloud. We’ll also discuss steps to take when your migration initiative goes beyond rehosting, requiring the assessment of alternative migration approaches, such as re-platforming and refactoring.

Critical Considerations

When moving on-premises business-critical applications to the cloud, there are critical considerations that span technical, operational, and business domains. Below are three key components not to be overlooked when defining your cloud migration strategy:

• Establishing a shared vision: Ensuring you have set goals and an executive sponsor.
• Understanding your why: Why are you migrating to the cloud in the first place?
• Defined business impact: What impact do you expect from your migration efforts and are your goals realistic based on the chosen approach?

Establishing a Shared Vision

The landscape of on-premises systems is often governed by many stakeholders, both business and IT, with competing goals, risk profiles, and expected outcomes from a migration effort. Having a clear vision for your rehost initiative with key roles and responsibilities defined is critical to the timeliness, investment, and overall success of your project. Finding an executive sponsor to unite the various groups, make decisions, and define the business goals and expected outcomes is vital in risk management.

As part of creating this shared vision, the executive sponsor needs to ensure:

• Goal Alignment: Having a shared vision among various business and IT stakeholders set direction and expectations for the project. A shared vision allows all parties, including vendors and internal resources, to understand the goal(s) and the role they’ll play for the project.
• Sufficient Budgeting and Resource Allocation: Appropriate budget and resources must be allocated for executing tasks related to this partnership, before the start of the migration effort to ensure timely project completion.
• Proper Documentation of Existing Systems: Critical information about on-premises systems and operations is often either insufficient or missing entirely. System documentation is mandatory to migrate systems and uphold their intended purpose.
• Product Ownership: On-premises business application suites are often acquired or internally developed. Original vendors may be out of business, so products are no longer viable. Conversely, the custom product may no longer be supported or understood due to missing source code. An owner needs to be designated to determine the future of the product.
• Organizational Change Management: Without user adoption, your cloud migration will fail. Change management efforts enable cloud technology adoption and require proper planning and execution from the start.

The considerations outlined above should be discussed up front, and partnerships among stakeholder groups must be established to accomplish the intended goal(s) of migration under executive sponsor leadership.

Understand Your Why

You’ve heard the stories about failed cloud migrations. Those stories often start with misaligned expectations and a rushed execution, which are among the top reasons cloud migrations result in a backslide to on-premises environments. Migrating to the cloud isn’t a silver bullet – not every organization will experience cost savings or even immediate functionality improvements from a rehosting project but there are many opportunities for cost avoidance and optimization of spend.

As an IT director or manager, it’s critical to ensure executive-level sponsors understand how different migration approaches align to anticipated outcomes. There’s often pressure from leadership to migrate to the cloud, and understandably with countless cloud benefits and the many challenges associated with aging on-premises solutions. However, understanding and communicating what’s realistic for your organization and how different approaches will address various business goals is crucial.

Data Center Evacuations & Unsupported Technology

Organizations migrating based on a mandated data center evacuation or the security and compliance risks associated with unsupported or end-of-support technology often look to a rehost strategy as a first step. This helps accomplish the business goal of reducing technical debt or remediating compliance concerns quickly.

Reaping the Benefits of Cloud-Native Solutions

There are many other reasons organizations look to the cloud, such as staying competitive, increasing time to value, or the ability to innovate. To fully realize the cloud outcomes that motivate these decisions – including greater flexibility, scalability, data security, built-in disaster recovery options, and improved collaboration – additional planning and refactoring of on-premises applications are often required. In these cases, sometimes we see a rehost as the first stage (as leadership wants to see quick results or has made a public commitment to migrate to the cloud), followed by more advanced modernization efforts.

To get to the root of goals and expectations, consider the following questions as you build your roadmap:

1. What are your business objectives for cloud adoption, and how will they help further the company vision?
2. Is there a set timeline to complete the cloud migration effort?
3. What internal and external resources are available to support a cloud migration?
4. How many applications are in your portfolio, and do you plan to migrate everything, or are you considering a hybrid model approach?
5. What are the technical requirements and interdependencies of your applications? How will you assess cloud readiness?
6. What are the necessary governance, security, and compliance considerations?
7. Who will be responsible for moving workloads to the new cloud platform? Who will perform the migration, and manage the workloads? Will you be doing it by yourself, or will it be a shared initiative?
8. How do you intend to use automation to reduce manual efforts and streamline provisioning and governance?

As you answer the questions above, you may find that a rehost effort is sufficient. Likewise, you may choose to explore a lead horse application approach as part of your migration strategy to better understand the value derived from various modernization tactics.

Uncovered Benefits of the Cloud

If your organization is interested in exploring cloud benefits that go beyond what a rehost effort can provide, migration options that are more involved than rehosting may be worth your consideration. Organizations looking to modernize through re-platforming or refactoring may be motivated by cloud benefits such as:

• Faster time to market, product release cycles, and/or pace of innovation
• Enriched customer and end-user experiences
• Improved employee technology, collaboration, and processes
• Better reliability and networking speeds
• Reduced cost of labor and/or maintenance
• Ability to leverage emerging technology
• Built-in disaster recovery options
• Flexibility and scalability
• Data security
• Cost allocation for budgeting and showback/chargeback
• Move from Capex to Opex (or realize Capex by buying resource commitments)

If you are facing tight timelines to migrate, a rehost effort can get you one step closer to realizing the above benefits. Through an initial migration, you can look to a proof of concept to gain a further understanding of the business impact various approaches have to offer while incrementally progressing cloud transformation.

Challenges

While rehosting is a faster, less resource-intensive migration approach and a great first step into the cloud, it comes with challenges and limitations.

The primary limitation of migrating certain on-premises applications to the cloud is the application’s inherent cloud compatibility. Specific applications have internal and external dependencies which limit their ability to take advantage of more advanced cloud benefits once rehosted.

While rehosting allows you to modernize the application environment, resulting in outcomes such as reduced Data Center costs, other cloud benefits aren’t fully realized. Outcomes such as elasticity and the ability to take advantage of cloud-native features are not available with a strictly rehost strategy.

While more cost-effective than on-premises hosting, sometimes it can be more costly to run applications in the cloud when rehosting, versus re-platforming or refactoring without a FinOps strategy to master the unit economics of cloud for competitive advantage. To show fast progress, rehosting is often a great transitional stage for working towards a cost-effective cloud solution, especially for organizations on a tight timeline. During this stage, managing cloud costs and realizing cloud value with a FinOps practice is key.

Feeling Stuck?

If you’re stuck in analysis paralysis, work with a consultant that’s been through various migration projects, from start to finish, and understands the common challenges and complexities of different approaches.

Whether you’re considering Azure, Office 365, Power Platform, or another cloud platform, AIS has a range of Adoption Frameworks and Assessments that can help you understand your options. With our help, create a shared vision, and align business goals to the appropriate migration approaches.