File server to SharePoint: planning files, permissions and the migration

Technically, a file server can simply be copied to SharePoint. For the new storage to work day to day, folders, permissions and ways of working need to be settled first. Drawing on around 15 migrations from a file server to SharePoint and Teams, I describe what I look at during preparation and how the move can be split into manageable steps.

Clearing out before anything moves

A file server that has been running for many years holds more than current work. Old project versions, duplicate copies and folders nobody opens any more. Before every migration I therefore clear out together with the client. What is no longer needed does not move. What has to be kept but is no longer edited gets a place of its own.

Then there are technical limits. In SharePoint the full path of a file, meaning the folder names plus the file name, may be no longer than 400 characters, and a single file no larger than 250 GB. Deeply nested folders with long names quickly hit the first limit. A scan before the migration shows which files are affected, and I can then rename or move exactly those.

Libraries instead of deep folder trees

On a file server, storage usually grows downwards: a drive, under it departments, under those projects, then years and subfolders. SharePoint works better when it grows sideways. A site or a team contains several document libraries, and ideally these hold hardly any subfolders. Copying the folder structure one to one is therefore rarely a good idea.

I set the permissions per library, and I do it before the data moves. Anyone with access to a library sees everything in it. That is easier to follow than rights set on individual folders deep in the tree that nobody can trace later.

Which folders become which library or which team is the client’s decision. Beforehand I explain how Teams and SharePoint fit together and what a given split means for day-to-day work. Then we agree together how people will work. The result looks different for every client. For a planning firm that moved its project storage from a file server to SharePoint, the target structure came out of a workshop with the management. There, a half-day basic training session for the whole team was part of it.

What moves to SharePoint and what does not

SharePoint plays to its strengths with files that several people work on: editing at the same time, versions, sharing, access from anywhere. For some data that adds little.

It is worth planning and writing down this lifecycle in advance. What happens to a project once it is finished? Does it stay in the library or move elsewhere, and after how long? SharePoint is too expensive for long-term archiving. Each tenant gets 1 TB plus 10 GB per licence, and anything beyond that costs money every month. There are considerably cheaper options for a long-term archive, such as an archiving solution like AvePoint Opus or partly automated archiving to a NAS or file server on site. Microsoft itself offers a cheaper storage tier for inactive content with Microsoft 365 Archive.

How long does a migration from a file server to SharePoint take?

A large part of the work happens before any data is transferred, in my experience around 70 per cent of the time: inventory, clearing out, target structure, permissions, planning the training. Depending on the scope this takes four to six weeks, and in simple cases less than a week. The remaining 30 per cent is the migration itself, monitoring it, checking afterwards and the training. That part can usually be condensed into about a week. With large amounts of data the transfer alone takes longer, because the speed depends on the connection and on how many files there are.

I transfer the data with AvePoint Fly, Microsoft’s SharePoint Migration Tool or PowerShell, depending on the project. The tools copy reliably, but they do not check whether the result makes sense. So I run the migration in waves and check every run. At the planning firm there were 219 migration jobs, which I matched against the project list beforehand. I reworked special cases one by one.

How much training do staff need?

More than a single session. Working in the cloud is different from working on a file server, even when the OneDrive client makes the libraries look like familiar folders in Explorer. Anyone left to find their own way in Teams and SharePoint easily makes mistakes, gets frustrated and works less efficiently than before. Files end up in the wrong places, teams spring up without any plan, and anyone who does not understand the sharing features quickly shares more than intended. That then becomes a data protection and data security problem.

I therefore train in several sessions rather than one long day. Nobody takes in hours of new knowledge alongside their daily work. I plan 120 minutes for a basic introduction to Teams and OneDrive in a small group of up to ten people. For broader topics such as Planner or OneNote in SharePoint, three to four sessions of 90 to 120 minutes each work better. I group the topics, and between sessions there is time to try the new things out in everyday work. Questions and problems from that time go into the next session.

Frequently asked questions

Can I simply keep the folder structure from the file server?

Technically yes, but I advise against it. SharePoint works with several document libraries and few subfolders, and you grant permissions per library. Deep folder trees also run into the 400-character limit for the full path.

Which files should stay on the server?

Often large video, audio and CAD files, and generally files nobody works on together. File type, size and access are what decide. PDFs and images are the exception, they move to SharePoint. For finished projects that only need to be kept there is cheaper storage than SharePoint.

Is a single training session enough to get started?

It is enough for a short introduction, but usually not for daily work. I plan a basic introduction of 120 minutes for up to ten people, and for further topics such as Planner or OneNote three to four follow-up sessions, with time to try things out in between.

Sources

• Path length, file size and storage per tenant: Microsoft Learn – SharePoint limits (as of September 2026)
• Planning a file share migration: Microsoft Learn – Guide to migrating file shares to OneDrive, Teams, and SharePoint (as of September 2026)
• SharePoint Migration Tool: Microsoft Learn – Overview of the SharePoint Migration Tool (SPMT) (as of September 2026)
• AvePoint Fly: AvePoint – Fly (as of September 2026)
• Cheaper storage tier for inactive content: Microsoft Learn – Overview of Microsoft 365 Archive, pricing model (as of September 2026)
• Sharing links and external sharing: Microsoft Learn – Manage sharing settings for SharePoint and OneDrive (as of September 2026)