Deletions, conflicts, and safe use
Most synchronization surprises come from two events: a file was deleted on one side, or the same file was edited independently on both sides. O&O AutoBackup exposes both in the preview so you can decide before data changes.
How deletion propagation works​
| Mode | If a file is deleted on the left | If a file is deleted on the right |
|---|---|---|
| Backup | Destination history remains available | Destination should not be edited manually |
| Copy | Right-side copy stays | No change is sent back to the left |
| Merge | The right copy returns to the left | The left copy returns to the right |
| Mirror | The right copy is removed | A left copy recreates it on the right |
| Two-way | The deletion is applied to the right | The deletion is applied to the left |
Mirror and Two-way normally move removed or replaced files to the Windows Recycle Bin first. That is a helpful safety net, but not a retention policy: Recycle Bin capacity and cleanup are controlled by Windows. Keep a Backup pair when the files matter.
Renames can look like copy plus deletion​
O&O AutoBackup detects renames where possible so a moved file does not need to be copied again. If identity cannot be established—for example across some storage types—the preview may show a create at the new path and a removal at the old path. The final folder can still be correct, but review large unexpected operations before continuing.
When the same file changed on both sides​
A conflict exists when both copies changed since the previous synchronization. Under Advanced, choose the policy that matches your workflow:
- Keep the newest — use the modification time. Convenient, but dependent on accurate clocks and timestamps.
- Keep both — preserve both variants so you can compare them. This is the safest general choice when edits are valuable.
- Left wins — always use the left copy for a conflict.
- Right wins — always use the right copy for a conflict.
- Skip the file — leave the conflict unresolved for manual attention.
The policy applies to actual conflicts, not every ordinary one-sided change.
A safe first synchronization​
- Make a versioned backup of both folders.
- Give the pair a directional name.
- Run manually before enabling a schedule.
- Read the preview totals and inspect every proposed deletion.
- Test with a small, non-critical folder if the mode is new to you.
- Confirm the result on both sides.
- Only then enable automatic or continuous operation.
Continuous synchronization needs extra care​
Continuous mode reacts after a quiet period following changes. It is convenient, but it shortens the time between a mistake and its propagation. For Mirror or Two-way, retain a separate versioned Backup pair and avoid using both sides while a large reorganization is still in progress.
What to do after a wrong synchronization​
- Stop the pair so another run cannot compound the problem.
- Check the Recycle Bin for files removed or replaced by synchronization.
- Do not make broad edits on both sides while diagnosing the event.
- Restore from the independent Backup pair to a separate folder.
- Compare and verify before putting files back into synchronized locations.
These modes are doing their job when they propagate a deletion. The protection against a mistaken deletion is a separate versioned backup—not a hope that synchronization will ignore it.