There are two basic synchronization variants
depending on how many folders of a folder pair you are actively working on:
- If both folders contain your work files and you want changes
(creates, updates, and deletes) to flow in both directions, then select Two way.
Database files are required to determine the directions and will be created
automatically after the first sync.
- If only one folder contains your work files and the other is for backup, then select the Mirror variant.
The left folder will be the source and the right folder the target of the synchronization.
In order to handle special synchronization scenarios you can
also set up Custom
rules based on the categories determined after folder comparison.
variant can be viewed as an example of
such a customization: It is just like Mirror
but adapted to avoid file deletions.
Detect Moved Files
FreeFileSync is able to detect moved files on one side and can quickly apply the same move on the target side during
synchronization instead of a slow copy and delete. To make this work, FreeFileSync requires a file system that
supports file IDs
(as alternative to file paths) and database files
to compare the current file system state against the time of the last synchronization.
The Two way
variant already creates database files, therefore, detection of moved files is always active.
variant however, does not use the database files to find synchronization directions, so detection of moved files
is not enabled by default. If you don't mind the creation of the database files, you can enable this feature by
selecting the Detect moved files
- Detection of moved files is not yet possible when synchronizing a folder pair for the first time.
Only beginning with the second sync the database files are available to determine moved files.
- Detection is not supported on file systems that don't have (stable) file IDs.
Most notably, certain file moves on FAT file systems cannot be detected.
Also file accesses via SFTP do not support move detection.
In these cases FreeFileSync will automatically fall back to "copy and delete".