Core 1.1.0 · beta
Two-way sync
A backup normally copies files one way: from the source folder to the destination folders. Two-way sync keeps all of these folders the same. A file you add, change, rename or delete in any of them ends up in all the others.
One idea first
Which folder is the source?
The source folder is the one you picked first. Every change goes to the source folder first, and from there to the other destination folders.
This does not matter for everyday use; it only decides where a file goes first. The one place it shows: if two locations change the same file at the same time and you chose Keep the source folder's version, the source folder's version is the one that keeps the name.
Turning it on
Choose Two-way sync as the backup mode
Pick it for a new backup, or switch an existing one-way backup over.
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Choose the mode
Open Backups and add a backup, or open the settings of an existing one. Under Backup mode, choose Two-way sync.
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Check the rules below it
Some choices change meaning in two-way sync, and two of them are not available. See rules that change in two-way sync.
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Save, look at the preview, confirm
Before the backup is enabled, CloudDrive compares the folders and shows what will happen: how many files exist only in one place, how many differ, how many are already the same. Nothing is changed until you confirm.
The first two-way pass copies files that exist only in a destination back to the source folder — or leaves them alone, if you chose that under Files that exist only in a destination folder. Nothing is deleted during this first pass.
Conflicts
When the same file is changed in two places
Choose what happens under When the same file is changed in two places.
Keep both versions (the default)
The other version is kept next to the file with a name like
report (conflict copy 115 Documents 2026-09-14 15-30-12).docx, in every location. Nothing is lost; you decide which one to keep.Keep the newer version
Only possible when both folders are cloud folders, because only cloud storage keeps a reliable time for each file. Otherwise both versions are kept.
Keep one side's version
Choose Keep the source folder's version or Keep the destination folder's version. The other version is moved to the history folder.
You can change the words added to a conflict copy under Conflict copy label.
Changed in two destination folders, not in the source
The rule above does not apply here. The newer version wins when both are cloud folders; otherwise the version in the first destination folder wins. The other version is kept as a conflict copy in every location.
Deletions
Deletions are not mirrored by default
Unless you turn on Sync deletions, a file you delete in one folder stays in the others.
With Sync deletions on, a file deleted in one folder is removed from the others according to the delete rule:
| Delete rule | What happens to the file in the other folders |
|---|---|
| Move to history folder (the default) | Goes to a .clfs_history folder next to where it was |
| Move to recycle bin | Goes to the recycle bin where the storage has one; elsewhere, to the history folder |
| Delete permanently | Deleted outright — only after you confirm this in the settings |
| Keep | Stays in the other folders |
If many files disappear from one folder at once — a disk that was not mounted, a folder emptied by mistake, a virus — CloudDrive does not delete them elsewhere. It waits for you. The backup shows Waiting for confirmation; open the sync issues and choose Apply deletions (they were meant) or Restore files (bring them back from the other folders). The limit is 20 files and the share you set under Deletion safety limit.
The same protection applies to changes: when a large part of a folder is rewritten at once, the changes wait for your confirmation. Choose Accept changes or Restore from the source folder.
Old versions
The history folder
Replaced and deleted files are kept in a hidden folder named .clfs_history next to where they were.
Versions replaced by the Overwrite rule are kept for the number of days set under Keep replaced versions for — 0, the default, keeps them for ever. Everything else stays until you delete it yourself.
Timing
Cloud folders and timing
Local folders are watched, so a change is picked up within seconds. Cloud folders are checked on the scan schedule: a change you make in another app appears after the next scan.
Set a scan interval
When one of the folders is a cloud folder, set a scan interval — 15 minutes is a good start.
On 115, Baidu and 123, a scan can tell from a folder's time whether files were added to it or removed from it, so folders that did not change are not listed again on every scan.
A file renamed in another app does not change its folder's time. Such a rename is found by the thorough scan CloudDrive runs on its own every few scans, at most a day apart; it runs even when no regular scan is scheduled, and Automatic thorough scan under the advanced two-way settings sets how often, or turns it off. To look into every folder right away, use Rescan on the backup.
Browsing a cloud folder checks it right away
Whenever CloudDrive lists a cloud folder again for any reason — you browse it, open it from a mounted drive, or copy something into it — the new list is compared with what the sync knows about the folder, and a difference starts a sync of that folder within seconds.
So a file added in another app appears in the other locations as soon as you look at its folder, and otherwise after the next scan.
Scope
Which locations can take part
Can take part
Local folders, most cloud drives, SMB / SFTP / WebDAV / S3, and encrypted folders.
Cannot (and say why when you add them)
- The root of a cloud drive — pick a folder inside it
- A read-only cloud drive
- A search-results folder
- Storage with no reliable modification time, FTP for example
A folder taking part in two-way sync may not overlap or nest inside another backup's folders. The reason is in the FAQ.
Rules that change in two-way sync
- Skip as the replace rule is not available: a changed file must be able to replace the older copy. Use Keep history versions or Overwrite.
- Delete source after backup is not available: the source folder must keep its files.
- Sync delete from destination, the one-way option, has no effect; use Sync deletions instead.
Day to day
Issues, pausing and starting over
Sync issues
Anything that needs your attention is listed under the backup: conflicts, deletions or changes waiting for confirmation, a folder that could not be compared, a folder that another CloudDrive instance is also syncing. Each entry says what to do. Dismiss hides an entry without changing any file.
One sync program per folder
Do not let another sync program, or another CloudDrive instance, manage one of these folders. CloudDrive writes a small hidden file named
.clfs_sync_ownerin each folder to notice this; if another instance is found, that folder is left out until the other instance stops. You can turn the marker file off under the advanced settings.Pausing
Pause two-way sync, on the Backups page under resource limits, stops every two-way backup from copying, renaming or deleting anything. Scans still run and record what they would do, so you can see what will happen before you resume.
Starting over
Reset sync index makes the backup forget what it has synced so far. The next scan compares every folder again, as on the first run. Nothing is deleted.
FAQ
Frequently asked questions
A file I deleted came back
Sync deletions is off, or the deletion happened while the folder could not be reached. With Sync deletions off, the other folders keep the file and, on the next scan, it is copied back only if it was changed there. Turn on Sync deletions to mirror deletions.
Where did my old version go?
In the .clfs_history folder next to the file, or in a conflict copy next to it.
Why does the backup say “Waiting for confirmation”?
Many files disappeared or changed at once. Open the sync issues and choose what to do; nothing is deleted or overwritten until you do. See the deletion safety limit.
Can I use one folder in two backups?
Not a folder that takes part in two-way sync. As soon as one of the backups is two-way, its folders may not overlap or nest inside another backup's folders — two engines on one folder would copy back and forth and cascade deletions. Two one-way backups are not restricted, as before.
Does it work with 115, Aliyun, Baidu and other cloud folders?
Yes. Changes made in the official apps are picked up on the next scan; see cloud folders and timing.
How do I stop it?
Switch the backup mode back to One-way backup, disable the backup, or remove it. The files stay where they are.
Something off in the beta?
Two-way sync is still in beta, so tell us when something does not look right. Bugs are best filed as GitHub issues, where they are tracked; the Telegram group is usually staffed, and email works too.