The option „Remove files not on source“, which you can find you can find in the Destination tab in the sync item’s settings, behaves differently depending on the sync type.
- One-way sync: all files/directories that are not on the source (anymore) and are not excluded will be removed. You can choose to remove excluded files, too, by checking the option „Remove excluded files“.
- Two-way sync: a file that exists on either the source or the destination will be removed only if its modification date is older than the last sync and it is not excluded (please read more about how single files are compared in two-way syncs). If a sync is run for the first time, no file will be removed. The option „Remove excluded files“ will remove excluded files from both the source and the destination.
- One-way move: because all successfully copied files will be removed from the source, no file will be removed from the destination. Only the option „Remove excluded files“ will be considered.
The option „Remove excluded files“, which you can find in the Advanced tab in the sync item’s settings, deletes all files that are excluded by any of the filters in the Exclude tab of a sync item’s settings. As an example, this option can be useful to delete hidden files left over by a previous copy performed in the Finder. In this case it is recommended to enable this option only at the beginning, run the sync once, and then keep it disabled, so that it will leave hidden files such as .DS_STORE files (which store Finder metadata) and the .Spotlight-V100 directory (which contains the Spotlight index) alone.