SharePoint Migration Guide

With the increase in remote and hybrid working, it's become increasingly important to centralise key data in a way that's accessible to teams working anywhere. On-premise file servers are becoming redundant, being replaced by modern cloud-based storage solutions such as SharePoint Document libraries and Azure Storage. A poorly executed migration can disrupt productivity for months, create security vulnerabilities, and cost thousands in rework. This comprehensive guide walks you through planning and executing a successful migration from traditional file servers to SharePoint Online—ensuring your organisation gets it right the first time.

Many organisations already use productivity tools such as Microsoft Teams, yet we see scenarios where some key data is stored within Teams SharePoint sites while other data remains on physical file servers. This fragmentation often leads to:

Storing information in Teams SharePoint sites is excellent until you need to secure individual folders. While creating private channels is one method, it's not necessarily the neatest way to separate and secure sensitive information. A properly planned migration provides a structured, secure, and collaborative foundation for your organisation.

Before diving into planning, you need a clear picture of what you're working with. Many organisations discover during migration that they have massive amounts of unused, outdated, or redundant data—and moving all of it is wasteful and expensive.

Pro Tip: Use this assessment to clean up your data before migrating. Migrating 500GB of clean, organised data is faster and cheaper than migrating 2TB of cluttered, outdated data.

It's imperative that adequate time is dedicated to planning your migration. Rushing this phase leads to security issues, user confusion, and expensive rework later. Here are the key things to establish early:

The answers to these questions will aid in setting up your new folder structure and assigning custom security permissions via security groups. It's worthwhile spending extra time reviewing the folder structure, checking for any blocked inheritance, or running a PowerShell script against the file server to extract all security permissions into a CSV file for detailed review.

There are three primary approaches to organising your data in SharePoint. Each has distinct advantages depending on your organisation's structure and size:

Many migrations fail because organisations underestimate complexity or time required. Be realistic about what can go wrong and plan accordingly.

Rushing these phases is the #1 reason migrations fail. Better to add 2 weeks to planning than 2 months recovering from security breaches or failed migrations.

Communication is critical to migration success. Inform teams early and clearly about what's changing and what to expect from the new system.

Important Discovery: If a folder is open for everyone (read or read/write) on a file server, some users may never realise they have access. When data moves to SharePoint, recently changed files appear in the user's SharePoint explorer or Microsoft Office home screen. This visibility shift means some users may think they have new permissions when they could always access that data—it's just now more visible to them.

Recommendation: Review each open folder with the local folder owner. Determine if such folders should truly remain open to everyone or if permissions should be restricted during migration.

Permissions set on the file server must be accurately replicated in the new structure. This is one of the most critical phases of any migration—missed permissions cause security issues and user frustration.

Step-by-Step Permission Analysis

1. Create a Permissions Inventory

Review all on-premise folders and create a spreadsheet including:

• Folder names and paths
• Current permissions (which users/groups have access)
• Associated Active Directory groups
• Permission levels (read, edit, full control)

2. Extract Permissions at Scale

For larger migrations, use PowerShell to extract all permissions. This is especially important for organisations with inheritance blocked 1-2 folders down from the root—these are easily missed and can result in users having access to data they shouldn't.

3. Review Group Memberships

Get a list of users in each assigned group. Ensure group membership is current and accurate.

4. Create Security Groups in Azure AD

Recreate permissions groups as security groups within Azure Active Directory. You have two options:

• Azure AD Connect (Hybrid Approach): For large migrations, use Azure AD Connect to sync on-premise groups to Azure AD. This saves time but requires proper planning. Download Azure AD Connect
• Manual Creation (Clean Break): For smaller organisations, manually create groups and assign permissions. This ensures a clean break from on-premise Active Directory.

The Migration Mapping Document

Create a comprehensive spreadsheet documenting the entire migration plan. Use these column headers:

Once complete, share this document with file server owners and stakeholders. Ensure they agree to the new structure and permissions. This alignment prevents misunderstandings and secures buy-in from key stakeholders.

Once you've completed your permissions analysis, implement these in SharePoint:

This approach ensures your SharePoint permissions exactly mirror your on-premise structure while leveraging Azure AD for centralised access management.

With planning, permissions analysis, and Azure AD groups in place, you're ready to migrate data. Follow this sequence:

Migration doesn't end when files are moved to SharePoint. The weeks following migration are critical for ensuring adoption and addressing issues.

Success Metric: File server access drops to near zero. If users are still accessing old file servers weeks after migration, adoption is failing and needs intervention.

Establishing Governance & Best Practices

Now that data is in SharePoint, establish governance to ensure it stays organised and secure:

Without governance, SharePoint quickly becomes as messy as the old file servers. Establish these practices early to maintain order and security long-term.