The predictable and cost-efficient lure of the cloud is becoming increasingly hard for companies to resist. Many companies are making cloud migration a priority. According to a cloud computing study by IDG, almost one-third of total IT budgets will be allocated to cloud computing in 2021.
With companies spending such a significant amount of money on the cloud, it’s essential they migrate as efficiently as possible. There isn’t just one way to move an application to the cloud, however. Migration can take many different forms, and success can hinge upon whether you choose the right strategy. For most organizations, that means choosing from one of these five popular methods.
A rehost strategy, also known as lift-and-shift, involves moving an entire infrastructure to the cloud without changing anything. You simply lift the code out of its current environment and shift it to another.
This is considered the simplest migration method, writes Narendar Nallamala, a partner at Ibexlabs. It’s also the most time-efficient and requires the fewest resources since you aren’t making changes to the data or code.
There are plenty of other benefits to rehosting. The speed with which rehosting migrates applications to the cloud keeps disruption to a minimum. There’s also potential for improved performance and to expand capacity while reducing on-premises costs.
Not everyone is keen on the lift-and-shift strategy, however. Software engineer Andy Macdonald believes a pure lift-and-shift strategy never works. “It definitely makes sense to make as few changes as possible when you’re moving a big, hefty and terrifyingly complex platform into the cloud,” he writes. But in doing so, you miss out on many of the benefits cloud providers have to offer. Macdonald cites benefits such as trying out ideas in test environments, and leveraging their novel infrastructures or their automation capabilities.
This approach is similar to rehosting, except organizations optimize systems prior to rehosting. That’s why Stephen Orban, general manager of AWS Data Exchange, calls it the “lift-tinker-and-shift” strategy.
With replatforming, the emphasis is on small optimizations while keeping the system’s core architecture the same. “You may be looking to reduce the amount of time you spend managing database instances by migrating to a database-as-a-service platform like Amazon Relational Database Service (Amazon RDS), or migrating your application to a fully managed platform like Amazon Elastic Beanstalk,” he explains.
Replatforming falls into the Goldilocks region between rehosting and refactoring an application, says Urvashi Melwani at Srijan. It’s a cost-effective way of achieving some of the cloud benefits you may miss with a simple rehost.
This migration option is not as fast as rehosting, though, warns Dattatri Radhakrishna, vice president of engineering at Whatfix. That’s because of the modifications that need to be made prior to the move. It doesn’t take that much more time, however. “The exact time frame varies depending on the application and what modifications you are making, but relatively speaking, it is not significantly more time-intensive than rehosting,” Radhakrishna writes.
Under a repurchasing strategy, organizations move legacy systems to a cloud-based (usually SaaS) provider. Moving your bookkeeping to Xero or your CRM to Salesforce are both examples of a repurchase strategy.
This strategy is known as “drop and shop,” explains Aled Sage, vice president of engineering at Cloudsoft. When applicable, it can be the fastest and least risky way to migrate to the cloud. It also significantly reduces the in-house skills needed to manage the system.
There are several drawbacks to repurchasing, he warns. Among them are a loss of control and a lack of data sovereignty. You don’t control new features being released, and you don’t know where data is backed up or how it’s managed.
How intensive a migration effort this is will depend on the replacement products you purchase, writes Florian Wirthensohn at Txture. “Some SaaS-replacements for on-premise products from the same vendor offer an option to quickly migrate data with little effort or even automatically. Some providers offer analysis tools to assess the to-be-expected migration effort.
“However, this might not be the case when switching to a product of a different vendor or if the migration path has been interrupted due to neglected maintenance of the on-premise application.”
Refactor or Re-Architect
A refactoring or re-architecting strategy goes considerably further than either rehosting or replatforming. In most cases, engineers will completely reimagine the way a system is built using cloud-native features.
“Application re-factoring/re-architecting implies significant changes in a legacy application, such as transforming a legacy monolith architecture into independent, self-contained microservices,” writes Andy Lipnitski, IT director at ScienceSoft.
“This migration scenario helps leverage all kinds of cloud services for easier development, operation and innovation, as well as the cloud capabilities for scalability, availability, portability, and resilience with self-recovery and dynamic loading.”
Often, refactoring will be driven by an organization's need to add features or grow performance in a way that can’t be achieved using legacy architecture, says Dob Todorov, CEO at HeleCloud. The sheer amount of work that takes place makes this the most expensive cloud migration option, though it can also be the most beneficial long-term.
That’s because organizations that refactor their architecture can take advantage of as many cloud features as possible, says Aater Suleman, CEO and cofounder of Flux7. This results in lower monthly costs than rehosting or replatforming.
Retire or Retain
Some assets won’t be worth migrating to the cloud right now. Others won’t ever be ready to migrate. In these cases, retaining legacy applications is a valid strategy.
“You should only migrate what makes sense from both a business and technical perspective,” says Justin Spears, product management leader at NetApp. “An alternative strategy would be to employ a hybrid cloud model where some of the application (or data) reside on prem but still are able to leverage the computer and elastics powers of the cloud.”
Other applications that have been migrated to the cloud already are often better retired, however. It’s simply not worth keeping certain legacy applications on your system. But that doesn’t mean you should delete everything completely.
“The best practice for legacy application retirement is to archive the legacy datasets into a cloud archive, which includes the ability to intelligently recognize, read, and manage (retention/disposition) the legacy application's data formats – before the legacy application is decommissioned,” writes Bill Tolson, vice president of global compliance at Archive360.
In doing so, your organization will always have access to retired data for regulatory purposes while achieving the cost savings that may well have been the point of the cloud migration in the first place.
Get Professional Help for the Move
Ultimately, you should choose the migration strategy that will provide your business with the most impact and value, says Susan Moore at Gartner. Each strategy comes with different costs and risks. “The key is to weigh all options to help identify the extent to which each will have the desired effect — with the minimum effort and maximum positive impact.”
A well-thought-out strategy and an experienced partner are key if you want to execute a successful cloud migration that benefits your business now and in the future.