Most organisations that migrate file shares to SharePoint want the same result: files people can find, share safely and open from anywhere. The trap is treating the move as a copy. A mapped drive that has grown for many years holds duplicates, abandoned folders, paths nested ten levels deep and permissions nobody can explain. Copy it across as it is, and you get the same mess in a new place, now easier to find through search and Copilot.
This post sets out a practical order of work, the Microsoft tools that do the moving and the limits worth checking before you start.
Why not just copy everything across?
File shares and SharePoint are organised differently. A file share is one big tree of folders, with access set folder by folder. SharePoint works better as a set of sites, each with its own libraries, owners and members, joined up with hubs and navigation. Microsoft recommends creating sites and organising them into hubs instead of building subsites, and the same thinking applies to folders: flatter is easier to find, to share and to secure.
Copying everything also moves old access problems. If the whole company could open a folder on the old drive, it can open it in SharePoint too, and search and Copilot work within each person's access, so wide access becomes much easier to stumble on. Our post on the SharePoint oversharing check before Copilot explains why. A migration is the cheapest moment to put access right.
How to migrate file shares to SharePoint: the steps
1. Take an inventory
List each share and top-level folder, who uses it, roughly how much it holds and when it was last changed. Ask each department to name an owner for its content. This list drives every later decision, and it becomes your register once the move is done.
2. Decide what to keep, archive or delete
Not everything deserves a place in the new system. Old project folders, duplicate copies and personal files on shared drives can be archived, moved to people's own OneDrive or deleted, in line with your retention rules. Agree those rules with each owner, in writing, before anything moves.
3. Design the structure first
Map the content you are keeping to sites and libraries. A common pattern is one site per team or function, with a few libraries in each, rather than one library holding everything. Keep folder depth shallow and names short. Where people need to find documents across teams, plan hubs and navigation now, alongside your intranet design and navigation if you have an intranet.
4. Plan permissions for the new structure
Set access at site or library level through each site's own groups, and avoid copying every folder and file permission from the old drive. SharePoint has limits here. Microsoft's published SharePoint limits support up to 50,000 unique permissions in one list or library but recommend a general limit of 5,000, and you cannot break inheritance on a list, library or folder holding more than 100,000 items. Designing access for the new structure, instead of carrying the old one over, keeps you well inside those limits.
5. Check the content against SharePoint limits
Scan the content before the real move. Two checks catch a lot of problems:
- Path length. The entire decoded file path, including the file name, cannot be longer than 400 characters in SharePoint and OneDrive. Deep folder trees with long names break this more often than people expect.
- File size. Each file can be up to 250 GB.
If staff will sync libraries to their computers, Microsoft recommends syncing no more than 300,000 files in a single library for optimum performance. That is a good reason to split very large shares across several libraries.
6. Pilot, then move in waves
Move one team first, ask them to work in SharePoint for a while and fix what they find. Then move the rest in planned waves, with each owner confirming their content arrived. Make each old share read-only once its content has moved, so nobody keeps saving to the old location.
Tell people what is changing and when, and show them where their files now live. A one-page note on opening, sharing and syncing files in SharePoint saves a lot of questions in the first week.
7. Look after it afterwards
A clean migration stays clean only if every new site has an owner and a review date. Keep the inventory from step one as your register, and check access on sensitive sites regularly.
Which Microsoft migration tool should you use?
Microsoft offers two tools for file share migrations, and both report on what moved and what did not.
| Question | SharePoint Migration Tool | Migration Manager |
|---|---|---|
| Where it runs | Installed on a computer, with PowerShell support | From the SharePoint admin centre, with agents installed on computers or virtual machines |
| Sources | File shares, and SharePoint Server 2010, 2013, 2016 and 2019 | File shares, plus Google Workspace, Box, Dropbox and Egnyte |
| Scale | One machine runs the migration | Several agents share the work, grouped for performance |
| Before you move | A scan and assess step | Prescans and file exclusions |
| Who can run it | A SharePoint admin or site admin, with read access to the source | A Global admin or SharePoint admin, with Windows read access to the shares |
The SharePoint Migration Tool is free and suits a single share or a smaller organisation. Migration Manager suits larger moves, because you can spread the work across several machines and track every task from one place. For file share sources, the server holding the data must support SMB 2.0 or later.
Whichever you use, run a small test task first. Read the report, open a sample of the migrated files in SharePoint and check who can see them before you schedule the larger waves.
Where APPS 365 can help
Our SharePoint migration and tidy-up service follows this order: inventory and plan, structure first, consolidate and move, clear duplication on the way and set permissions properly from day one, with training so people use the new home. Each move is priced after a free call, with a written fixed quote before work starts. Once the content lands, GovernPoint scores each SharePoint Online site from A to F for oversharing, so you can see the new SharePoint staying tidy as it fills up.
Before you start
Permissions are the part most worth getting right, and the free 10-point SharePoint check before Copilot gives you a list of what to look for. To talk through your file shares and a sensible plan, book a free 30-minute call with APPS 365.
