External drives · Upgrading, transferring and backing up the drive
Why won't Transfer Drive or Backup Drive let me pick a drive?
Short answer: The destination must be an external APFS or Mac OS Extended drive with room for everything on your current drive, and not already a Storage Studio drive for this Mac. Slow drives need confirming; unsuitable ones can't start.
Before anything copies, the destination is checked. It must be:
- an external drive — your internal disk and network shares are never offered;
- formatted APFS or Mac OS Extended;
- big enough for everything on your current drive;
- not already a Storage Studio drive for this Mac.
A quick speed test runs too. A slow drive or one with cautions asks you to confirm; an internal, network or too-small drive can't be started at all. If nothing suitable is connected you'll see No Drive Available — plug one in and press Refresh.