By default, a sync item consists of two bases: a source and a destination.

When changing the sync type to two-way sync, there is no concept of source and destination anymore, since every base is source and destination at the same time.

All bases need to have the same type: they all need to be either directories, packages or regular files.

Note: SyncTime syncs the source with the destination. It does not sync the source with the file inside the destination that has the same name as the source; doing so would make it less flexible as it wouldn’t allow to sync files with different names. When the source is a directory, you can easily create one on the destination from inside the Open panel by clicking the New Folder button. When the source is a regular file or package (such as the Photos Library), you need to copy it manually to the destination first so that you can then select it in SyncTime.

You can define additional bases in the General tab of the sync settings by clicking on Add more bases at the bottom and then on the + button below the list of bases.

Having more than two bases changes how a sync behaves depending on the sync type. These changes are described in the following sections.

One-way sync / one-way move

Multiple sources are virtually merged and mirrored to all the destinations.

Files on different sources with the same name but with different modification dates or sizes are considered a conflict, causing an error to be logged.

If the option Remove files not on source is enabled, a file on a destination is removed only if it is not present anymore on any of the sources.

Note: multiple sources are meant to bring files spread between different directories or volumes together into a single directory. If instead you have different directories and want to sync each one into its own destination directory, it is recommended that you either:

• create separate sync items or
• select the common parent directory as the source, exclude it and then include only the desired subdirectories (see Filters).

Two-way sync

In a two-way sync, the bases are always virtually merged and files that have changed on a base are mirrored to all other bases, hence there is no distinction between source and destination. In particular, between syncs, a file may be modified only on one base or it will be considered a conflict, causing an error to be logged.