Switching to a new drive: Transfer Drive and Backup Drive

Outgrown your drive, or want a spare copy of it? Storage Studio can copy everything it keeps on your external drive — every moved folder and app — to another external drive and check the copy.

• Transfer to a New Drive… copies, checks, and then switches over: your relocated folders and moved apps now point to the new drive.
• Back Up to Another Drive… copies and checks, and keeps using the current drive. The other drive holds a complete spare copy.

In both cases the current drive is never written to or deleted from. After a transfer it still holds a full copy.

Step by step

1. Plug in both drives.
2. From the More menu, choose Transfer to a New Drive… or Back Up to Another Drive…. The Transfer Drive or Backup Drive window lists the other external drives.
3. Select the drive to copy to. Storage Studio checks it and shows:
   • This drive looks good., This drive can be used, with cautions. or This drive can't be used., with reasons;
   • its speed, from a quick read and write test;
   • Needs about so many GB, and how much is free on that drive.
4. Click Transfer… or Back Up…. If the drive had cautions or is slow, you're asked Continue anyway? first, with Transfer Anyway or Back Up Anyway.
5. Watch the progress: how much is Copied, the Speed and the Time left. Then the copy is checked.
6. For a transfer, Storage Studio then switches over, updating every relocated folder and moved app to use the new drive. If any moved apps live in a folder macOS protects, such as Applications, you're asked for your password once.
7. Done. A transfer says Now using the new drive; a backup says Backup complete and offers Reveal Backup in Finder.

%% caption: Transfer to a new drive compared with backing up to another drive
flowchart TD
  A[Pick the other drive] --> B[Checks - format, space, speed]
  B --> C[Copy everything Storage Studio keeps on the current drive]
  C --> D[Check the copy matches]
  D -->|Does not match| X[Stop - current drive unchanged]
  D -->|Matches, Backup| E[Backup complete - keep using the current drive]
  D -->|Matches, Transfer| F[Re-point moved folders and apps to the new drive]
  F --> G[Now using the new drive - old drive still has a full copy]

What the new drive needs

• It must be external — your Mac's own disk isn't offered.
• It must not already have a Storage Studio folder for this Mac. If it does, it's refused with that reason — choose a different drive. Drives that Storage Studio has set up before are marked Already set up in the list.
• It needs enough free space for everything on the current drive, with a small margin.
• Its format is checked the same way as when you set up a drive — see Drive formats.

While it runs

• Pause, Resume and Cancel are at the bottom of the window.
• The copy keeps going if you close the window or Storage Studio, and continues if a drive is unplugged and plugged back in — it shows Waiting for the drive… in the meantime.
• The switch only happens after the copy has been checked. If anything doesn't match, it stops with The copy couldn't be verified. Your current drive is unchanged.
• If the switch itself can't finish, Storage Studio says so — your old drive still has everything, and you keep using it.

After a transfer

Your relocated folders and moved apps open from the new drive. The old drive still holds the full copy; keep it until you're happy everything works, then reuse it as you like.

What's kept

The copy keeps each file's contents, name, modified date and permissions, Finder tags and other extended attributes, hard links and shortcuts. It is accepted only after every file's contents have been compared with the original. A few details that a folder move keeps — such as access lists and Finder's Locked flag — aren't part of this copy; compare What a move keeps.

See also: Choosing an external drive, Setting up your drive, Data Backup for versioned backups of your Mac's folders.