Back Up OneDrive to Synology NAS: Methods and Limits

Yes, you can back up OneDrive to a Synology NAS. The usual approach is to use Synology Cloud Sync to download or synchronize cloud files to a NAS folder; for a separate, more recovery-oriented copy, use a compatible backup workflow and check that it preserves the files you need.

What OneDrive-to-NAS backup means

OneDrive is Microsoft’s cloud file service, while a Synology NAS stores files on local network-attached drives. Connecting them can give you a local copy that remains available if your internet connection is down, and can help you retain files independently of the OneDrive account. It does not automatically make that copy a complete backup.

The distinction matters: synchronization tries to make two locations match. If a file is deleted or changed in OneDrive, a two-way sync may propagate that change to the NAS. A backup is intended to provide recoverable earlier or independent copies. A sensible setup may use Cloud Sync for convenient access and a separate NAS backup or snapshot strategy to protect against accidental changes, ransomware, or device failure.

Choose the right Synology method

• Cloud Sync: Synology’s package connects supported cloud services, including OneDrive, with a NAS shared folder. It can download files, upload files, or synchronize changes according to the task and options selected. It is the straightforward choice for keeping a local copy of ordinary OneDrive files.
• Synology Drive or other NAS backup tools: These can help protect data already stored on the NAS, such as by keeping versions or another backup copy. They do not, by themselves, fetch OneDrive content; pair them with a method that first brings the cloud files onto the NAS.
• Third-party or scripted tools: Some users choose these for filtering, scheduling, or special workflows. Check that the tool still supports Microsoft’s sign-in and API requirements, and understand how it handles permissions, metadata, and deletions before relying on it.

Package availability and exact options can depend on the NAS model, DSM release, and current package support. Check Synology’s package documentation for your device before planning around a specific feature.

Set up Cloud Sync for a local copy

1. Sign in to DSM with an account that can install packages. Open Package Center, find Cloud Sync, and install it if it is offered for your NAS.
2. Open Cloud Sync and add a connection. Choose Microsoft OneDrive and complete the Microsoft sign-in and consent prompts in the window that opens. Use the account that contains the files you intend to copy.
3. Select the OneDrive folder or folders to include, then choose a destination shared folder on the NAS. If you want a download-only copy, configure the task’s direction accordingly and verify the displayed direction before saving.
4. Review options for filtering, scheduling, conflict handling, and file changes. For a backup-style copy, avoid settings that allow NAS-side deletions or edits to be sent back to OneDrive unless that is deliberate.
5. Save the task and allow the initial transfer to complete. Check Cloud Sync’s status and compare a few representative folders and files in DSM File Station with their OneDrive counterparts.

Menu wording can vary between DSM and package versions. If Cloud Sync does not appear, confirm compatibility and package availability rather than assuming the NAS can never connect to OneDrive.

Understand sync direction, deletions, and versions

A one-way download task is generally safer than two-way synchronization when the goal is to keep a NAS copy. It reduces the chance that an accidental change made on the NAS will be written back to the cloud. Still, verify how the selected task handles deletions: “one-way” describes the direction of transfers, but settings may determine whether removed source files are also removed from the destination.

For protection against mistaken edits and deletions, enable versioning or snapshots where supported and appropriate for your NAS configuration. Keep in mind that a snapshot on the same NAS is not a substitute for another independent copy: drive failure, theft, fire, or a major NAS compromise could affect both. A robust plan can follow the 3-2-1 principle: maintain multiple copies, on different types of storage, with at least one copy kept off-site.

Also consider OneDrive features that are not ordinary files. Online-only placeholders, shared files owned by someone else, Microsoft 365 collaboration data, and some account-specific settings may not be copied in the same way as files stored directly in your OneDrive. Test with the material that matters most instead of assuming every cloud feature is archived.

Common problems and practical checks

• Sign-in fails: Reconnect the account from Cloud Sync and complete any current Microsoft authentication prompts. An expired authorization or changed account security settings can interrupt access.
• Some files are missing: Check folder selection, filters, permissions, and whether the files are actually in the connected OneDrive account. Compare the NAS task’s status and logs for skipped or failed items.
• Transfers are slow: The initial copy may take considerable time, especially with many small files or a limited upload/download connection. Leave the NAS online and monitor progress rather than repeatedly creating duplicate tasks.
• Files disappear from the NAS: Review sync direction and deletion handling immediately. Pause the task if necessary, then inspect the cloud and NAS copies before changing settings or restoring anything.
• Names or metadata differ: Cloud platforms and file systems do not always represent every character, attribute, or collaboration feature identically. Validate important filenames, timestamps, permissions, and special file types.

Security, storage, and maintenance

Give the connected account only the access required for the task, and protect DSM with a strong unique password and multi-factor authentication where available. Keep DSM and packages updated, restrict administrative access, and avoid exposing NAS management services directly to the internet unless you have a well-understood, secure reason to do so.

Estimate the space required by checking the size of the OneDrive content you plan to copy, then leave room for growth, versions, and other NAS data. Cloud Sync is not a way to bypass Microsoft storage limits, and it cannot retrieve files the account no longer has access to. Review the task periodically, check for errors, and perform a test restore: open or restore a few files from the NAS copy to confirm it is usable.

Frequently Asked Questions

Can Synology Cloud Sync back up OneDrive automatically?
Yes. Create a Cloud Sync task connected to OneDrive, select the source folders and NAS destination, and configure its direction and schedule. Check task status and confirm the copied files appear on the NAS.

Will deleting a OneDrive file delete it from my Synology NAS?
It depends on the task direction and deletion settings. Inspect these options before enabling synchronization, and test with a disposable file if the behavior is unclear.

Is Cloud Sync the same as a backup?
No. It can create a local copy, but synchronization may also carry deletions or unwanted changes across. Use versioning, snapshots, or another independent backup to improve recovery options.

Can I back up a OneDrive account I do not own?
Only if the account owner or Microsoft permissions grant access to the relevant content, and the tool can access it. Shared items may behave differently from files owned and stored directly in your account.

What should I do if Cloud Sync is unavailable on my NAS?
Check Synology’s current compatibility and package information for your model and DSM version. If it is unsupported, consider a maintained alternative that uses Microsoft sign-in, and test its restore and deletion behavior before depending on it.

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