Plan an application modernization strategy

2025-05-13

A strategic approach to modernization accelerates cloud and AI adoption. A modern platform helps you improve costs, become more agile, and accelerate innovation and development velocity, but there’s no single way to get there. You need to assess the unique needs of each application through multiple lenses to arrive at a target that maximizes your return on investment (ROI).

This section focuses on application-level decision-making. It helps you narrow your modernization choices based on a variety of factors, including six widely used rationalization paths known as the 6 Rs of rationalization.

IaaS vs. PaaS

Depending on your level of cloud adoption, you may be evaluating whether to target infrastructure as a service (IaaS) or platform as a service (PaaS). IaaS can be the right choice when you need granular control over your infrastructure, and you have the bandwidth to manage the operating systems and applications. However, PaaS gives you the flexibility to modernize any application or framework.

IaaS offers great control and flexibility, but PaaS stands out for its unique benefits:

Enhanced productivity, thanks to built-in development tools, middleware, and database management systems, which streamline the development process and boost productivity.
Faster time-to-market. By eliminating the need to manage infrastructure, PaaS enables developers to focus on building and deploying applications quickly.
Reduced management overhead since the cloud provider handles infrastructure maintenance, updates, and security. Your IT teams are free to concentrate on strategic initiatives.
Scalability and flexibility. PaaS platforms are designed to scale effortlessly, accommodating growing workloads without requiring manual intervention.
Innovation and agility through a flexible environment where developers can experiment with new technologies and methodologies without worrying about infrastructure constraints.
Enhanced security, identity management, privacy, and compliance—all the responsibility of the cloud providers. Consequently, these areas have become their core competencies, sparing you from the significant overhead associated with managing these business-critical requirements. You can easily take advantage of the security, identity management, privacy, and compliance measures that PaaS and other cloud-based options provide.

The choice really depends on your specific business needs, technical requirements, and strategic goals. The following sections can help you decide.

Control vs. simplicity

Choose IaaS when your enterprise requires granular control over the operating systems, middleware, and runtime environments. IaaS gives you the raw building blocks of computing, including virtual servers, storage, and networking, in addition to the highest level of flexibility and management control.
Choose PaaS when you want to simplify and streamline development and deployment processes and minimize operational overhead. PaaS supplies ready-to-use development environments where you can create and deploy applications without managing the underlying infrastructure.

Development flexibility vs. speed

Choose IaaS for flexible control over your development environment. IaaS typically requires more time and effort to maintain than PaaS.
Choose PaaS when you want the efficiency of preconfigured environments, integrated development tools, and automated workflows. Developers can focus on coding and innovation rather than infrastructure management.

Manual vs. automatic scalability

Choose IaaS when you want more customizable control or to meet specific regulatory needs. You’re responsible for managing your virtual machines, ensuring that the infrastructure can handle increased loads, and maintaining and monitoring the infrastructure.
Choose PaaS when you want applications to scale automatically as demand changes. PaaS handles load balancing and resource allocation for you, reducing the burden on your IT teams.

Self-managed vs. predictable costs

Choose IaaS when you want control and have the expertise to manage your infrastructure. IaaS can be cost-effective, but costs can quickly escalate as you add resources and consider maintenance.
Choose PaaS for a more predictable cost structure, with pricing based on usage and the services you consume. Organizations particularly benefit from the reduced management overhead.

Familiar vs. unknown

Choose IaaS for the familiar choices it provides. If you’re new to cloud computing, you can speed migration using IaaS to rehost existing on-premises applications with few code changes and without the steep learning curve.
Choose PaaS when you’re ready to fully embrace cloud computing and cloud-native application architectures. PaaS deployments are well tested and documented, giving you the details you need to make sensible adoption decisions.

On-premises, hybrid, or cross-cloud?

Where your applications run affects your choice of cloud-native capabilities, business flexibility, operations, and governance models. Your landscape may include on-premises infrastructure in addition to hosting environments from one or more cloud vendors. The following table summarizes common approaches and factors to consider.

Factor	Traditional on-premises	Private cloud on-premises	Hybrid cloud	Cross-cloud
Governance model	Self-provided	Self-provided	Shared control	Shared control
Cloud-native capabilities	None	IaaS	Some PaaS	Services from multiple cloud providers
Business flexibility	Very limited	Very limited	Balanced	High
Operations	Managed and controlled in-house	Hypervisor-centric; complicated security and compliance	Complex to manage, use, monitor, and control	Complex to manage, use, monitor, and control; promotes choice

On-premises: Traditional datacenters and private clouds

The traditional stronghold of enterprise IT is the on-premises datacenter. It hosts your organization’s applications and gives you complete control over data and infrastructure. This setup is often favored for its security and compliance with stringent regulatory requirements. However, a traditional setup demands a significant upfront investment plus ongoing maintenance and service costs. It also makes scalability challenging. Importantly, facility services such as power, cooling, and space can fall outside the visibility and concern of IT, even though they impact your bottom line.

Instead of physical servers, a growing number of organizations are turning to virtualized solutions. For example, you can use VMware to relax some of the physical server constraints through virtualization and to introduce a more flexible approach for IT infrastructure. You’ll hear these environments referred to private clouds. Though private, they’re limited by their focus on infrastructure, and so they aren’t truly cloud-native.

The following table highlights key considerations of traditional on-premises datacenters and on-premises private clouds, both of which limit business flexibility.

Factor	On-premises: Traditional	On-premises: Private cloud
Governance model	Self-controlled data, applications, and infrastructure with self-provided and self-maintained measures of security and compliance	Self-controlled data, applications, and infrastructure with self-provided and self-maintained measures of security and compliance
Cloud-native capabilities	None	IaaS-centric virtualization
Operations	In-house management, use, monitoring, and control	Hypervisor-centric management, use, monitoring, and control that can complicate security and compliance measures

Hybrid cloud: The best of both worlds

When you blend on-premises infrastructure and cloud services, you get the hybrid cloud model. You can share data and applications within your own datacenters and across public or private clouds. Hybrid offers the flexibility to continue using existing investments while enjoying the scalability and cost-efficiency of cloud services.

The hybrid cloud approach is more complex to manage and keep secure. You need robust integration and orchestration tools to ensure seamless operation. The following table highlights key considerations.

Factor	Hybrid cloud pros and cons
Governance model	Shared control of data, applications, and infrastructure between your organization and the cloud provider; appropriate on-premises and cloud-based security and compliance measures are needed
Cloud-native capabilities	Hybrid combination of on-premises landscape plus cloud-native PaaS
Business flexibility	Good—you can use the best of on-premises and cloud-based resources
Operations	Inherently complex to manage, use, monitor, and control

Cross-cloud: More choices and challenges

With a cross-cloud strategy, you orchestrate multiple cloud services from different providers. A multicloud approach mitigates the risk of vendor lock-in and enhances resilience by distributing your workloads across various platforms. You can select the best solutions for your needs, optimizing performance and cost.

However, a cross-cloud strategy demands sophisticated management expertise. The complexity adds operational challenges as your teams ensure multicloud interoperability and implement comprehensive monitoring and governance to maintain control. The following table highlights key considerations.

Factor	Cross-cloud pros and cons
Governance model	Shared control over data, applications, and infrastructure between your organization and multiple cloud providers; appropriate security and compliance measures are needed across cloud providers.
Cloud-native capabilities	Hybrid combination of services from multiple cloud providers, but you must maintain separate software configurations for each cloud.
Business flexibility	Promotes choice, avoids vendor lock-in, promotes resilience.
Operations	Inherently complex to manage, use, monitor, and control; promotes choice.

Next steps

Continue planning your strategy using the 6 Rs of application modernization.