Choosing an external drive

Storage Studio moves folders and apps to an external drive and leaves shortcuts behind, so you'll be opening those files from the drive every day. The drive's speed and reliability become part of your Mac's. A fast solid-state drive (an SSD, including NVMe drives in an enclosure) connected directly to your Mac is the best fit.

What Storage Studio checks

When you pick a drive in Choose External Drive (see Setting up your drive), Storage Studio checks:

• It's external. Your Mac's own disk can't be chosen — the whole point is to move things off it.
• It's local. Network drives are refused.
• Its format. APFS and Mac OS Extended pass; exFAT is allowed with a warning; FAT32 is refused. See Drive formats.
• Its speed, if you ask. Run benchmark writes a 128 MB test file to the drive, reads it back and deletes it, which takes about 5–10 seconds.

Speed

The speed test sorts drives into three groups:

If either speed falls into a lower row, the drive gets that result. A drive in the middle row works, but relocated folders and moved apps open more slowly, and long copies take longer. If you use a slower drive, such as a spinning hard disk, set Parallel transfers in Data Parking's settings to 1 or 2.

Connection

• The drive's details show its connection type as Protocol, for example USB or Thunderbolt.
• Leave it connected while you work. Moved apps and relocated folders can't be opened while it's unplugged — see When your drive is disconnected.

Capacity

Choose a drive with plenty of room for what you plan to move, plus space to grow. If you later want to switch to a bigger drive, Transfer to a New Drive needs the new drive to have at least as much free space as everything Storage Studio keeps on the current one, with a small margin — see Switching to a new drive.

Storage Studio uses one external drive at a time for moving folders and apps.

%% caption: How Storage Studio judges a drive you pick
flowchart TD
  A[Pick a drive] --> B{External and local?}
  B -->|No| X[Not suitable]
  B -->|Yes| C{Format}
  C -->|APFS or Mac OS Extended| D[Compatibility looks good]
  C -->|exFAT| E[Usable with warnings]
  C -->|FAT32| X
  D --> F[Optional speed test]
  E --> F
  F --> G{Fast enough?}
  G -->|Yes| H[Use This Drive]
  G -->|Slow| I[Usable, but expect slower apps and copies]

See also: External drive, Checking your drive's health and setup, What to know about exFAT drives.