People searching for “free file sync” often want a second copy of their work, not a complicated backup system. FreeFileSync can synchronize two folders, but its modes treat deletions differently. Choose the direction before the first run: Two Way moves changes both ways, Mirror makes the destination match the source, and Update adds changes without propagating source deletions to the backup side. If files have already gone missing, pause the sync task before changing its settings.
Decide whether you need synchronization or a backup
Synchronization keeps two locations aligned according to rules. A backup should also let you return to an earlier good state. Those goals overlap, but they are not identical. If a mistaken deletion is copied to the second folder, two synchronized locations may both lose the file. A separate versioned or offline backup protects against that kind of mistake. Begin by identifying which folder contains the work you actively edit and which one is supposed to protect it.
FreeFileSync is a real file-synchronization application. Its official synchronization manual describes three basic variants. Two Way sends creates, updates, and deletions in both directions. Mirror makes the right side an exact copy of the left, including deletions on the right when the source no longer contains an item. Update adds files to the backup side without deleting them there just because they were removed from the source. Read those rules before choosing a preset with a comforting name.
For a novice, the clearest starting question is: “Where should a file that I deleted by accident still exist tomorrow?” If the answer is “on the backup drive,” a mirroring task without versioning may not meet your needs. If both computers are actively editing the same project, Two Way might be appropriate, but you need to understand conflicts and recent changes. Keep a separately tested copy for important work regardless of the synchronization mode.
Three modes, three different deletion stories
Two Way: both folders can change
This is for two working folders where changes should move in both directions. FreeFileSync records state in synchronization database files after a sync so it can infer change direction later. That is helpful, but it also means a deletion can propagate. If two people edit the same document independently, do not assume a sync engine will merge their paragraphs. Discuss which copy is authoritative and keep prior versions.
Mirror: one source defines the result
The left side is the source and the right side is the target. The program makes the target an exact copy of the source. If you remove a folder on the left, a later Mirror run can remove its counterpart on the right. That behavior is correct for a mirror, but risky when you thought the right side was an archive. Use this mode only when you truly want that one-way exact state. Preview the proposed actions before synchronization.
Update: add to the backup without copying deletions
Update is often easier to understand for a simple accumulation of copied files. A source deletion does not cause that file to be deleted from the target. However, this does not make Update a complete backup strategy by itself. Replaced files, application data, and an untested destination still matter. Decide how older versions will be kept and how often you will check that files open correctly.
Do not build a plan from a table of modes alone. Think through a concrete accident: a folder disappears from your laptop just before the scheduled job. What will the chosen mode do to the external drive? Then consider a ransomware incident or a faulty file that overwrites a good one. A regularly connected synchronized drive may be exposed to the same event. That is why the external-drive backup checklist emphasizes testing a restore, not merely creating another folder.
Run a small rehearsal before trusting the job
Create two temporary folders that contain only disposable test files. Put a document on the left and a different one on the right. In FreeFileSync, choose those folders as the pair, select the mode that matches your intention, and compare them. Read the action preview before starting synchronization. You should be able to explain which files will copy and which, if any, will delete. If the preview surprises you, change the mode or stop instead of clicking through.
After the first run, alter a test file and remove another. Compare the folders again. This reveals the effect of your actual choices more clearly than a settings screenshot. Confirm the destination path and device identity; a different external drive can receive the same letter later. If you plan to automate the job, first make sure the test behaves as expected when the target is disconnected and reconnected. A missed run should be noticed, not silently mistaken for a fresh backup.
Move from test folders to real work only after you know how the preview represents creates, updates, and deletions. Start with a small noncritical project. Keep an independent backup while you learn. Check that the right destination contains the expected versions and that you can open them. Save the job configuration in a place you can find later, and record which side is the source. A future you—or a colleague—should not have to infer the direction from folder names alone.
When a sync has already removed a file
Pause scheduled runs immediately. Do not try to “sync back” at random; another direction can replace the surviving copy. Inspect both folders, the Recycle Bin on each Windows machine, any versioning location you configured, and cloud or system backups. If a copy still exists, duplicate it to a third healthy location before testing another synchronization. Check the file’s contents, not just its name and size.
Windows’ Recycle Bin may help for some local deletions, but do not assume every synchronized removal lands there. That depends on the task and environment. Look at the exact folders first. The Recycle Bin recovery page covers ordinary deletion checks. If the work folder and backup both lost the file, note which physical volume originally held the most recent version. That is the likely source for a recovery attempt, provided the device remains stable.
Drecov is Windows data-recovery software, not a synchronization engine. When a local file really is missing from a stable, recognizable disk, it can search the original location. Quick Scan offers initial results; Deep Scan can broaden the search if the source remains reliable. Filters and previews help identify supported documents, photos, and other files. Recover chosen results to another healthy device. Lost Partition Recovery is available when an entire partition is missing, but it does not reverse a sync rule, repair a failed drive, or promise restoration of overwritten data. Use the file recovery overview when neither synced folder nor its backups holds the needed local version.
⚠ Warning: Install it on a drive different from the one where your data was lost to prevent overwriting.
The source for this scenario is the local volume where the needed version last existed, not automatically the external destination. If the storage clicks, disconnects, or reports severe read errors, stop direct scans and seek imaging or professional help. Do not install recovery software on the source volume. Prepare a separate healthy target before you begin. A synced copy can overwrite deleted-file remnants on either side, so do not continue working in those folders while investigating.
Step 1: open Drecov and choose the original location
Launch Drecov on a working Windows system. Select the stable volume that held the missing file before synchronization removed or replaced it. Compare device size and known folder path. Do not scan a cloud account as if it were a local disk. If the PC will not start, first obtain compatible access to its stable drive from another Windows environment.
Step 2: check Quick Scan
Run Quick Scan. Search by filename, former folder, and file type when useful. Pay attention to dates and versions, but verify content rather than trusting a timestamp alone. If the document is already present in a versioned backup, use that working copy first. Software recovery is a fallback for actual local loss.
Step 3: broaden the search only if safe
If the needed version does not appear and the device is stable, try Deep Scan. Preview representative supported files. One readable page does not prove an entire project or archive is complete. Stop if the source begins failing. Repeated scanning does not repair hardware or recreate data that later writes have overwritten.
Step 4: save away from both active sync folders
Recover files to a separate healthy location outside the live folder pair. If the output is not where expected, check Drecov Folder or Recovery Folder on that destination. Open the recovered version and compare its actual edits. After protecting it, you can resume the synchronization job with revised rules. Otherwise the same task may remove the recovered file again.
⚠ Warning: Install it on a drive different from the one where your data was lost to prevent overwriting.
Make the next copy useful when you need it
Choose a mode that reflects your real workflow, not a guess that “two folders means backup.” For one active source and a protective destination, consider how you will retain versions when a file is edited or deleted. Store at least one independent copy that is not continuously exposed to the same changes. The right arrangement depends on your devices and how often you edit, but the test is simple: can you restore yesterday’s good version after today’s mistake?
Schedule a regular restore check. Pick a random recent document and an older project, copy them from the destination to a temporary folder, and open them. If the destination is missing a file, read the FreeFileSync preview and logs before adjusting rules. Do not fix a missing backup by launching a blind Mirror run. First determine which side currently has the good data. Then make the configuration clear enough that the next operator can recognize the source and target.
Conclusion
FreeFileSync can keep folders aligned, but alignment can also repeat a deletion or bad edit. Understand Two Way, Mirror, and Update; rehearse changes in disposable folders; and keep a separately tested backup for important work. If a local file has already vanished from a stable Windows volume, pause synchronization. Drecov can search that original location and save recoverable files outside the active folder pair, but it cannot undo an overwrite or replace a sound backup plan. Verify the recovered version before resuming the job.
⚠ Warning: Install it on a drive different from the one where your data was lost to prevent overwriting.
