Copy, Move, Sync or Two-way sync

The four folder operations in Data Transfers differ in two things: whether the source is left alone, and whether the destination is allowed to lose files. Copy never removes anything. Move removes the source after copying. Sync (one-way) removes files from the destination that aren't in the source. Bidirectional sync — the app's name for two-way sync — carries changes, including deletions, in both directions.

Side by side

Copy

Copy duplicates the source into the destination and leaves the source exactly as it was. Running it again sends only files that are new or have changed. A file at the destination that is newer than the one in the source is left alone rather than overwritten, and a file you deleted from the source stays at the destination.

Use it for: putting a copy of your photos in a cloud account, or sending a project folder to a colleague's shared folder.

Move

Move copies the files and then removes them from the source, so each file ends up in one place only. When the source is on your Mac, Storage Studio also tidies away the empty sub-folders the move leaves behind, but it always keeps the source folder itself.

Use it for: clearing old downloads off your Mac into a cloud account. If you're moving folders between your Mac and your external drive, Data Parking is usually the better tool: it checks the copy and leaves a shortcut behind.

Sync (one-way)

Sync makes the destination a mirror of the source. New and changed files are copied, and files at the destination that aren't in the source are deleted. Storage Studio doesn't keep a copy of what Sync deletes, so make sure the destination is a folder that should hold nothing else.

Example: you sync a Mac folder called Clients to Archive/Clients in a cloud account. Later you delete Old invoice.pdf from the Mac folder. On the next run, Old invoice.pdf is deleted from the cloud copy too. If you had saved a file straight into Archive/Clients in the cloud, that would be deleted as well, because it isn't in the source.

Use it for: keeping an exact off-Mac copy of a folder you only ever change in one place. Check the result with Dry run before the first real run. See one-way sync.

Bidirectional sync

Bidirectional sync keeps two folders the same when you change both. Add, edit or delete a file on either side and the next run carries that change to the other side, so a deletion on one side deletes it on the other. If the same file changed on both sides between runs, the app records it as a conflict in the transfer's Log.

The very first run for a pair of folders needs the First run for this pair box ticked in Advanced options, and that box must never be ticked again. Two-way sync and the First run box walks through it. See two-way sync.

Use it for: a folder you work on from two places, such as a working folder on your Mac and the same folder in a cloud account you also use on the web.

%% caption: What a deletion at the source does under each operation
flowchart LR
  A[You delete a file from the source] --> C{Which operation?}
  C -->|Copy| K[The destination keeps its copy]
  C -->|Move| K2[Nothing more happens; the file had already moved]
  C -->|Sync one-way| X[The destination copy is deleted on the next run]
  C -->|Bidirectional sync| Y[The other side's copy is deleted on the next run]

Download

The fifth choice, Download, isn't a folder operation: it fetches one file from a web link into a folder you choose, which is your Downloads folder unless you change it. The link has to point at a file, not a web folder. Large files arrive in pieces, so an interrupted download picks up where it stopped (see transfers and restarts).

See also: Data Transfers · Copying between two cloud accounts · Sync again and Run again · Files that change during a transfer