Moving Time Machine backups
QThe 1TB external disk I keep my Time Machine backups on is almost full. How should I move them to a replacement 4TB disk, so I can use that for backup storage? byMARKSASS
AThis depends whether your current backup store is a traditional HFS+ volume, or the more modern APFS. To discover which it is, select that volume in the Finder and use the Get Info command in the File menu. In the top section, its kind should be Volume, and the format will either be Mac OS Extended or APFS (case-sensitive).
Copying Time Machine backups from an HFS+ volume takes forever, is prone to error, but can be done. Copying them from APFS currently isn’t possible, because those backups are built on snapshots, which can’t be copied to another volume or drive.
When you start making backups to your new drive, Time Machine will probably insist it uses an APFS volume anyway. The best plan is to keep your existing backups as an archive. If you ever need to access them, they’ll still be available through the Finder rather than the Time Machine app. Then start a new backup set on the APFS volume Time Machine will create for you on the replacement drive.