FreeFileSync External SSD Backup Guide for Windows
Use FreeFileSync with an external SSD while avoiding wrong-drive, deletion, and disconnect mistakes.
Quick answer
Verify the SSD by volume label, capacity, and target folder because Windows drive letters can change after reconnecting devices.
What to check first
Start conservatively and review the comparison grid before using Mirror, which can propagate unwanted deletions.
Windows-specific factors
Keep versioning or another historical backup if deleted or overwritten files must remain recoverable.
Safer troubleshooting workflow
Do not disconnect the SSD during synchronization; inspect the log and destination after completion.
How to verify the result
Periodically restore representative files to prove that the backup is usable.
Frequently asked questions
Should I change sync mode to fix this?
Not until the underlying cause is identified. First verify paths, permissions, comparison results, and logs.
Is a successful sync the same as a verified backup?
No. Important data should be checked at the destination and periodically restored to a separate location.
Related: all FreeFileSync Windows guides