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Cloud Migration Strategy 2026: A Checklist for Moving Legacy Systems

Written by

Picture of Chris Wilson
Chris Wilson
Systems and Compliance  Officer
Chris managed the development and deployment of many Nexus software projects, before turning to work in Nexus’s internal business processes. His work on Nexus’s internal compliance involves subjects like data protection, client contracts and information security. He also selects and administers some of Nexus’s business systems.
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Key Takeaways

  • A successful cloud migration strategy in 2026 starts with auditing what you have, not moving it. Unchecked data migration from legacy systems is the fastest way to inflate costs and risk.
  • A clear cloud migration checklist should cover identity, storage location, security controls, and licensing before any workloads are moved.
  • Most SME migrations fail due to weak cloud migration planning and strategy, particularly around identity (Entra ID vs Active Directory) and file placement (SharePoint vs Azure Files).
  • Cloud migration data security must be built into the project plan from day one, with encryption, MFA, and conditional access enforced before users access migrated data.
  • An effective Azure migration checklist avoids a lift-and-shift approach by refactoring legacy servers into cloud-native services that reduce maintenance, improve resilience, and lower long-term costs.
  • Ongoing success depends on operational ownership. Hybrid environments require proactive monitoring and support, not just a one-off migration project.

For many UK organisations, 2026 marks the final turning point for on-premise hardware. The cost of maintaining ageing servers, combined with the strict enforcement of Cyber Essentials requirements, has made the argument for data migration from legacy systems undeniable. Keeping critical business data tethered to physical hardware in an office comms room is now a direct operational risk.

A successful move requires more than just a fast internet connection and a Microsoft 365 license. It demands a strong cloud migration strategy that accounts for application compatibility, data sovereignty, and the specific way your teams access information. When executed correctly, modernising your infrastructure removes the unpredictability of hardware failure and replaces it with a scalable, secure environment that grows with your business.

This checklist outlines the critical steps for planning your move, focusing on the foundational elements that ensure stability and security from day one.

Creating Your Cloud Migration Project Plan (The Audit)

The most common cause of migration failure (or spiralling cloud costs) is a lack of visibility into the existing estate. Moving data without auditing it first inevitably leads to paying premium cloud storage rates for obsolete files, duplicated records, and software that no longer serves a business purpose.

Your cloud migration project plan must begin with a ruthless discovery phase. That means mapping every workload, application, and dataset currently residing on your physical servers to determine its value. This is the time to archive historical data that’s legally required but rarely accessed, ensuring your active cloud environment remains lean and cost-effective.

Key audit actions include:

  • Identify Dependencies: Map which applications rely on specific legacy databases or hard-coded internal IP addresses. Breaking these links during the move causes immediate downtime.
  • Categorise Data Sensitivity: Segregate public data from sensitive PII (Personally Identifiable Information) or financial records. The classification dictates your security policies in Azure or SharePoint later in the process.
  • Assess Licensing Impact: Review how your current server software licenses transfer to the cloud. Microsoft’s Azure Hybrid Benefit, for example, can offer significant savings if valid on-premise licenses are applied correctly to cloud resources.


By establishing a clear inventory upfront, you prevent the ‘lift and shift’ of inefficiencies and ensure your new environment is optimised for performance rather than just capacity.

CASE STUDY: From Legacy Server to Serverless

When Progressive Roofing’s on-premises server reached end of life, they faced a choice: buy new hardware or modernise completely.

Instead of a direct lift-and-shift, Nexus audited their remote working needs and designed a fully serverless environment using Microsoft Azure and SharePoint. The result was that they eliminated the need for VPNs, secured their mobile workforce with Microsoft Defender, and massively reduced their ongoing infrastructure costs.


The Azure Migration Checklist: Specifics for Microsoft Environments

For most UK SMEs, cloud migration specifically means moving from a Windows Server environment to Microsoft Azure solutions. This is a shift in how your entire network authenticates users and stores files.

Internal IT teams often encounter issues here because the terminology looks familiar, but the behaviour is fundamentally different. A successful move hinges on two specific decisions: how you handle identity and where you put your files.

Businesswoman sitting at the desk indoors in office, using computer.

1. Identity: Entra ID vs. Active Directory for Cloud Migration

In a traditional setup, your Domain Controller is the heart of your security. In the cloud, that role shifts to Microsoft Entra ID (formerly Azure AD). The mistake many teams make is assuming Entra ID is a direct, like-for-like swap for their on-premise Active Directory. It isn’t.

Entra ID does not handle Group Policy Objects (GPOs) or legacy device management in the same way your old server did. Your Azure migration checklist must include a step to modernise management. That often involves deploying Microsoft Intune to manage devices over the internet, rather than relying on a local server to push out updates.

The benefit of this is that once configured, your staff can securely access company resources from anywhere, without needing a clunky VPN.

2. Storage: Azure Files vs. SharePoint for SME Migration Benefits

Where does the data actually go? You generally have two choices, and picking the wrong one can lead to an expensive error.

  • SharePoint Online: Best for hot data (active documents, collaborative Excel sheets, and HR files that multiple people edit simultaneously). It offers version history and real-time co-authoring, but is not designed to hold millions of archival PDFs or giant CAD files.
  • Azure Files: This is the correct home for your cold data (files that are rarely accessed, updated, or needed for daily work, but must be kept for reference, compliance, or legal reasons) or legacy applications. It mimics a traditional mapped network drive (the S: drive your team is used to) but lives in the cloud.


A smart cloud migration strategy usually involves a hybrid approach: moving active team folders to SharePoint for better collaboration, while shifting heavy archives and legacy application data to Azure Files to keep costs low and performance high.

Supporting Your Hybrid Infrastructure

Moving workloads to the cloud introduces new management layers that require constant attention. Internal IT teams often find that maintaining both legacy servers and a new Azure environment consumes time that should be spent on strategic growth.

Nexus Managed IT Services provides the operational safety net your business needs during and after this transition. We take responsibility for the 24/7 monitoring, security patching, and system maintenance of your entire estate. By handling the day-to-day complexity of your hybrid infrastructure, we ensure your internal team remains free to focus on high-value business projects.

 

Cloud Migration Data Security and Keeping Data Safe in Transit

Cyber security is often treated as an afterthought in migration projects, something to be configured once the servers are running. This approach introduces significant risk. When you perform data migration from legacy systems, you’re taking information out of its protective silo and moving it across the public internet.

A well-planned cloud migration strategy treats security as a constant requirement throughout the transfer process, not just a final checkbox.

1. Encryption Is Non-Negotiable

Legacy servers often store files in plain text because they sit behind a locked office door and a physical firewall. The cloud has no physical perimeter. All data must be encrypted both “at rest” (when it’s sitting in your Azure storage) and ‘in transit’ (while it’s moving).

Modernising your infrastructure allows you to enforce encryption policies that were impossible on older hardware. It ensures that even if a data packet is intercepted during the upload, it remains unreadable and useless to external threats.

2. The Shift to Zero Trust

The biggest cultural shift for internal teams is accepting that the office firewall no longer protects the data. Once your files are in Microsoft 365 or Azure, the primary security boundary becomes identity.

  • Multi-Factor Authentication (MFA): This must be enabled before the first user logs in. In 2026, MFA is the baseline standard for Cyber Essentials; migrating without it guarantees immediate compliance failure.
  • Conditional Access Policies: Instead of trusting everyone inside the building, you configure rules that verify the user, their location, and the health of their device before granting access.


By building these controls into the migration plan, you effectively bake in security from day one. It prevents the common scenario where teams migrate quickly to hit a deadline, leaving sensitive portals wide open to the internet.

Modernising Customer Experience

A complete cloud migration strategy shouldn’t leave your contact centre behind. While standard Microsoft Teams handles internal collaboration perfectly, customer-facing teams often need more sophisticated control than basic calling provides.

Luware bridges this gap by transforming Microsoft Teams into a strategic contact centre platform. It replaces legacy PBX hardware with intelligent, skills-based routing and real-time reporting dashboards, all native to the Teams interface. It ensures your customer interactions are as data-driven, resilient, and secure as your new cloud infrastructure.


Why Lift and Shift Isn’t a Strategy (Refactoring)

There’s a temptation to simply take your existing virtual machines and run them exactly as they are in the cloud. This is known as Lift and Shift, and while it’s the fastest route, it is rarely the most cost-effective.

Running a virtual server in the cloud 24/7 incurs high compute costs. True modernisation involves refactoring; changing how your applications work to use cloud-native features.

internet or telephone line cables and crimper
 
  • Server vs. Service: Instead of paying to run a Windows Server just to host a database, you migrate the data to Azure SQL Database. That removes the need to patch the operating system, reduces monthly costs, and improves reliability.
  • File Shares: Instead of a heavy file server, you move to SharePoint libraries or Azure Files, which scale automatically without you needing to provision extra hard drive space.

Refactoring requires more upfront planning, but it delivers the true promise of the cloud: an environment that requires less maintenance and costs less to run over the long term.

Refactoring vs. Relocating

True modernisation requires more than just a data transfer. If you simply move a legacy server to the cloud unchanged, you often end up paying premium hosting costs for the same old performance.

The Nexus Strategic Projects team specialises in re-architecting. We help you re-architect, not just relocate. We rebuild your workflows to use native Azure services, turning clunky file servers into streamlined Azure Files and heavy databases into scalable SQL instances, ensuring you get the full cost-efficiency of the cloud.

 

From Checklist to Reality and Future-Proofing Your Infrastructure

The decision to undertake data migration from legacy systems is rarely taken lightly, but in 2026, it is the single most effective way to secure your organisation’s future. Holding onto ageing hardware actively introduces risk into your daily operations. By following a structured cloud migration strategy, you move away from the unpredictability of physical servers and towards a resilient, scalable environment where your team can work securely from anywhere.

However, recognising the need for change is only the first step, and executing it without disrupting your business is the real challenge. A cloud migration checklist helps you plan the journey, but having an experienced partner ensures you actually reach the destination. 

Don’t leave your critical infrastructure to chance. 

If you’re ready to modernise your estate but aren’t sure where to start, book your free IT consultation with our strategic projects team today to review your current environment.

To see how we support hybrid and cloud-native businesses long after the migration is complete, explore our managed IT support services and discover how Nexus can protect your new digital foundations.


Article Sources

  1. Microsoft Learn. Select your cloud migration strategies. Accessed February 3rd, 2026
  2. National Cyber Security Centre (NCSC). Device security guidance.  Accessed February 3rd, 2026
  3. Microsoft. Azure Hybrid Benefit. Accessed February 3rd, 2026
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