Migrating file shares and SharePoint on-prem to SharePoint Online

Editor's note: This article was originally published in 2013 and has been updated for accuracy and to reflect current Microsoft 365 terminology and products

TL;DR: A good migration to Microsoft 365 starts with the destination, not the copy job. Plan your architecture, scan and clean your content, pilot with one small team, then move the rest in waves.

If your company still runs on file shares, you already know how it goes. Nobody can find anything, three versions of the same document are floating around, and someone has just asked who owns the "Final_v2_REAL" folder. SharePoint in Microsoft 365 fixes most of that, but only if you migrate with a plan. Copy everything over as-is and you'll have the same mess in a new place.

So how do you prepare for a migration from file shares, or from an existing SharePoint, to Microsoft 365? That's what we'll cover here.

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Your SharePoint architecture is the key

SharePoint is a big platform with a lot of possibilities. So the most important part of a migration isn't the move, it's the plan for what your content looks like once it lands.

Microsoft frames this as information architecture, and it covers more than folders: global navigation, hubs, local site and page navigation, metadata, search, and personalization. The building blocks you'll be working with are:

• Sites (team sites and communication sites), grouped by hub sites
• Lists and libraries
• Metadata: columns and content types, which Microsoft calls the two most important metadata elements
• Navigation, so people can actually find things

Why does it matter? Because there are far too many glorified file shares living in SharePoint. People never designed the structure the platform needs, so they never got the power they were paying for. Folders aren't evil, but Microsoft is clear that nesting beyond one or two levels hurts discoverability. Inventory what you have, decide what really needs to move, and build your architecture before you move anything.

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Migrating file shares to SharePoint Online

Easy, just press the magic button!

...If only it were that easy.

Microsoft's own guidance breaks a file share migration into five phases: planning, assessing and remediating, preparing your target environment, migrating, and onboarding your users. Here's how I'd think about each.

Decide what goes where. Not everything belongs in SharePoint. A file that's really one person's work can go to their OneDrive. Content a team works on together belongs in a shared library, like a SharePoint site or a Teams channel. This is also the time to ask what's redundant, outdated, or just not worth moving.

Understand what moves and what doesn't. Files, folder structure, and permissions come across, but explicit deny permissions don't, hidden Windows attributes don't, and URLs embedded inside your documents aren't converted. Share and NTFS permissions get mapped to SharePoint permission levels, and advanced NTFS permissions are dropped. If your file share permissions are a maze, now is the time to simplify them.

Scan and fix before you migrate. Microsoft's limits are worth knowing up front. Files can be up to 250 GB, the full path including file name can't exceed 400 characters, and a library can hold up to 30 million files and folders. Some file types and characters are also blocked. Migration Manager scans your file share sources automatically when you add them, and the SharePoint Migration Tool (SPMT) has a scan-only option. Both give you reports to work from. Fix the problem files now, not halfway through the migration.

Pick your tool. For file shares, Microsoft points you to Migration Manager in the SharePoint admin center. You install agents on your servers, and it handles the tasks, the progress tracking, and the reports. SPMT is the free desktop alternative and supports local and network file shares. A tool like ShareGate is the next step up if you want more control and reporting on top.

Start small, and keep it incremental. You don't need to wake up tomorrow and throw out every file share. Unless you want total chaos at work. Microsoft recommends a pilot with a small set of users to validate the process, performance, communication, and feedback. Both tools support incremental migrations, so you can run an initial copy in the background and re-run it to pick up new and changed files before a final cutover. A team that's feeling real pain finding documents makes a great pilot. They'll also become your champions for the next wave.

Plan your cutover. Remember that migrating copies your files. It doesn't touch the source. When you're ready, set the old file share to read-only so nobody keeps working in the wrong place. Microsoft recommends one cutover event rather than letting people work in both places, because that avoids duplicate copies.

Mind the clock. Microsoft throttles migration traffic more tightly during weekday business hours. Evenings and weekends have more capacity, and support can't lift the throttle. Schedule your big runs accordingly.

Bring your people along. Tell users what's changing and when, train them, brief your help desk before cutover, and plan for some downtime. That part isn't glamorous, but it's why some migrations stick.

None of this is quick, and it's the part that decides whether you end up with a real collaboration platform. Once you've moved things, ask yourself:

• Do the documents have the right content type and metadata?
• Can that metadata be reused on other sites so search gets the same terms?
• Does the content need approval before it's published?

If not, you're not using SharePoint to its full potential.

When it's done, reporting matters to be sure that all has been copied over to SharePoint Online, without any missing data or files.

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Migrating from SharePoint on-premises to Microsoft 365

If you're planning on migrating from your own SharePoint to Office 365, then the steps will be a little different. You'll already have a basic understanding of the structure of a SharePoint site and your previous experiences on the platform will make the transition a lot smoother.

The migration process could be a lot easier when migrating from SharePoint, as opposed to migrating from a file share. But it depends on you. Sometimes, it’s important for us, working in IT or SharePoint every day, to take a step back and realize that users couldn't care less what platform they're on.

For the most part, they don’t even know if they're using 2010 or 2013. Since SharePoint is a web-based platform on which we've built a collaborative environment, it’s easy for us to simply add hyperlinks to our new SharePoint without anyone noticing.

This being said, my biggest SharePoint Online migration success has been in a hybrid scenario.

We set up the new environment in Microsoft 365 using the best practices we'd learned, plus a few things we wanted to try. Then, department by department and site by site, I switched the links over to the new locations.

Users barely noticed. It was just another SharePoint site with some fresh branding. I moved content in a controlled way, on a timeline I fully controlled. With the right tools, moving from SharePoint on-premises to online can be secure and seamless.

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Recap: tips and best practices

• Explain the process to your users before you start, and keep them updated as you go.
• Pilot with a small team first, then move the rest in waves.
• Plan your governance and information architecture first, or you'll just have a web-based file share.
• Inventory and scan your content. Fix blocked file types and characters, long paths, and files over the limits.
• Simplify your permissions before you migrate. Deny rules and advanced NTFS permissions won't come across.
• Use incremental runs to keep the destination current until cutover, then set the old location to read-only
• Schedule large migrations for evenings and weekends.
• For on-premises SharePoint, scan with the SharePoint Migration Assessment Tool (SMAT), plan modern sites and hubs, and decide what to do with your workflows.
• Be ready with detailed reporting on what was migrated.
• Know what SharePoint is and what it can do before you start.

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‍Download: The ultimate SharePoint migration checklist