Back up to USB drives

1 Select the drive

Open Disk Utility from the Utilities folder and select the external drive in the sidebar. This has a single partition and is formatted with EXFAT for PC compatibility.

2 Erase the drive

Select the drive, not the partition, and then click ‘Erase’. Set the format to ‘Mac OS Extended (Journaled)’ and the Scheme to ‘GUID Partition Map’. Enter a name too.

3 Partition the disk

If you don’t want to use the whole drive for Time Machine backups, click ‘Partition’ and then click the ‘+’ icon below the circle. Drag the white dot to set the size.

4 View the partitions

The external USB drive has two partitions which appear as two drive icons on the desktop. They can have different uses. Select each drive in the sidebar for details.

5 Open Time Machine

Open System Preferences and open Time Machine. If a disk is already set, click it and remove. Otherwise click ‘Select Backup Disk’ to choose the drive and partition.

6 Choose the drive

The partitions on the USB drive appear as separate drives and either can be selected to store Time Machine backups. Click ‘Use Disk’ and tick the two checkboxes to finish.