Keep a OneDrive Copy During Migration

Cutover is Friday and your manager asks one question. If something goes wrong, can we get the old files back? You can, but only if you made a copy before the move, not after.

I ask this question on every OneDrive project. This guide shows how to keep a copy of OneDrive data during a migration, how to download all data from OneDrive, and which method fits which size, using facts from Microsoft's own pages.

Why Keep a Copy of OneDrive Data During a Migration?

A migration should copy, not move. A copy leaves the original where it is, so you can compare the two and go back if the result is wrong. That is the simplest rollback plan you can have.

Three events make a safety copy worth the time. A user is leaving and the account will be deleted. The tenant is changing and the old one will close. Or a large account holds files nobody can afford to lose. In every case, the copy is what lets you say yes when someone asks for a file in March.

In my experience, teams skip this step because the migration tool already copies the files. But the tool copy goes to the new tenant. A separate safety copy sits outside both tenants.

Which Method Fits Your Situation?

Choose by size and by how many accounts you have.

How do You Download All Data From OneDrive by Hand?

Microsoft's page on downloading files and folders from OneDrive gives the steps. Select items with the circle check box, or press Ctrl and A to select everything in a folder. Then select Download. Several items arrive as one zip file.

Know the limits before you start. Microsoft lists a 250 GB single file limit and 10,000 files per download. Compressed files like zip and mp4 are limited to 10 GB per zip file and 20 GB overall. Files protected by sensitivity labels or IRM that are over 4 MB may be left out of the zip, so download those separately.

Two more gaps matter. OneNote notebooks cannot be downloaded, and the zip includes a text file with an error instead. Also, you cannot download directly from the Shared view, so open the file and save a copy.

The sync app is the second manual option. Set the folders you care about to Always keep on this device, and OneDrive keeps full local copies. This works for one account on one PC, but it does not scale to fifty users.

How do You Keep a Copy of OneDrive Data During a Migration?

These are the steps I follow on every project. They work for one account or one hundred.

1. List every account and its size. Note which users are leaving and which accounts hold the most data.
2. Set retention for leavers first. Microsoft allows 30 to 3,650 days for a deleted user's OneDrive. Change it in the SharePoint admin center before you delete anyone.
3. Take a quick copy of key folders. Download or sync the folders that cannot be lost, like contracts and client files.
4. Copy full accounts with a tool. Use a migration tool to copy accounts to the new tenant and to a holding account. The source must stay read-only.
5. Verify the copy. Compare file counts and read the per-file report. Check a few large and important files by opening them.
6. Keep the source and the safety copy. Do not delete either until every user has signed off.

For leavers, read OneDrive files when an employee leaves. For one account to another, read how to copy OneDrive files to another account.

What does a OneDrive Copy Leave Behind?

No copy method carries everything. Downloads lose sharing, versions and OneNote notebooks. A tool copy is closer, but not complete.

RecoveryTools OneDrive Migrator copies OneDrive for Business between tenants and also within the same organization, so you can make a holding copy in the same tenant. It keeps original dates, can keep every version or the current version only, hash checks every file and never overwrites existing files. The source stays read-only.

It does not carry sharing links, Personal Vault, OneNote notebooks, the recycle bin, retention and legal holds, sync app and Files On-Demand settings or guests. List those before cutover and plan them separately. For versions, read OneDrive version history after migration.

For the full move, read how to migrate OneDrive from one tenant to another and OneDrive cross-tenant migration.

What are the Best Practices for a OneDrive Safety Copy?

• Copy before you change anything. A safety copy made after the move is a second migration, not a backup.
• Store it outside both tenants. A copy in the old tenant disappears when the tenant closes.
• Write down what is left out. OneNote notebooks and sharing links need their own plan.
• Check by opening files. Counts match even when a file is damaged.
• Keep the source read-only. Do not delete it until sign-off.

Which Mistakes Lose OneDrive Data in a Migration?

Four come up often. First, deleting a leaver's account before the copy is checked. Second, trusting a zip download without looking for left-out files. Third, keeping the only safety copy on a laptop. Fourth, forgetting OneNote notebooks, which Microsoft says cannot be downloaded.

My Verdict on Keeping a Copy of OneDrive Data

Copy first, move second. A safety copy outside both tenants is cheap, and it ends most arguments about missing files.

Use downloads for a few folders and a migration tool for many accounts. Then check the copy and keep the source until everyone signs off.

Frequently Asked Questions

Published 17 October 2026. Download limits and steps come from Microsoft's page on downloading files and folders from OneDrive. Retention range comes from Microsoft's page on OneDrive retention for deleted users. Product behavior comes from the RecoveryTools OneDrive Migrator page. Microsoft can change these limits, so check them before you plan.