Moving folders safely

Data Parking is the hands-on way to move folders off your Mac's built-in disk — to your external drive or to a cloud account. Choose Data Parking… from the More menu to open it. It's a two-pane window: your Mac on the left, the destination on the right, and the controls in the middle.

The three moves

Once both panes show folders with the same name, click Pair and the move buttons switch on.

• Move — the destination ends up matching what you moved. If something with the same name is already there, it is replaced. The original is removed after the copy is checked.
• Merge — combines what you moved into the matching folder on the other side. Anything that is only at the destination is kept; files with the same name are updated from what you're moving. The original is removed afterwards.
• Relocate — moves the contents to your drive but leaves the folder where it was, with each file replaced by a shortcut to its new home. Apps that read the folder still find everything where they expect it.

If a Move or Relocate would replace something already at the destination, Storage Studio stops and asks first. It names what will be replaced, says how many files that is, and asks you to type Replace to confirm — because what gets replaced isn't kept anywhere. Move, Merge or Relocate helps you choose.

%% caption: What happens when you move a folder in Data Parking
flowchart TD
  A[Tick folders on one side] --> B[Pair the two panes]
  B --> C{Which action?}
  C -->|Move or Merge| D[Copy to the other side]
  C -->|Relocate| D
  D --> E{Does the copy check out?}
  E -->|No| F[The move stops and the original stays where it was]
  E -->|Yes, Move or Merge| G[The original is removed]
  E -->|Yes, Relocate| H[Each original file becomes a shortcut]

Why it's safe

• The original is never removed until the copy has finished and been checked. The gear button sets how carefully each copy is checked: Fast (stat compare) is the default, Thorough (content hash) reads every byte, and Off (trust the copier) still checks sizes before anything is removed. See How copies are checked.
• Folders you're still working in are held back. By default a folder with a file changed in the last 12 hours isn't moved, so a half-saved project doesn't get copied mid-write. See When an app is holding a folder open.
• Pause or cancel at any time. Your originals aren't touched until the final step, so stopping part-way is safe.
• If the drive is unplugged while a folder is moving onto it, the move waits and carries on when the same drive comes back.
• A finished move can be undone. The move history lists completed moves with a Revert button, as long as the drive is connected and nothing new has been put at the original spot. See The Moves log and Moving a folder back.

What a move keeps

A move between your built-in disk and your external drive keeps each file's contents and name, its created and modified dates, its permissions, its Finder tags and other extended attributes, and Finder's Locked and hidden flags. Hard links and sparse files stay as they are, and shortcuts stay shortcuts. Custom access lists are kept when the drive can hold them. File ownership isn't carried over — external drives normally ignore it. The full list is in What a move keeps.

Moves to a cloud account keep what that provider supports — see Parking a folder in a cloud account.

See also: A tour of the Data Parking window, The shortcut left behind after a move, Data Transfers for copies and syncs you want to schedule.