seagate external hard drive time machine

Select a drive and click on the Use Disk button.

A window opens showing External Storage Drives connected to your Mac To open System Preferences - Click on the Apple icon > System Preferences

Click Done, the backup will start in 60 seconds.

If encrypting the drive, enter the password.

To open System Settings - Click on the Apple icon > System Settings Setting up the external drive to be used with Time Machine: Use this link for instructions on formatting your drive

For macOS versions for 10.6 (Snow Leopard) to 10.15 (Catalina) use Mac OS Extended (Journaled) also referred to as HFS+ when setting up a new backup.

For Big Sur and later, use Apple File System (APFS) when setting up a new backup.

MacOS requires that a drive be formatted with a specific file system to be used with Time Machine In this example, the internal drive is 250GB and just over 20GB are being used.Formatting a drive to be used with Time Machine: You should see a window like the one below. To find out how large your internal drive is and how much space is being used and how much is available, click on the internal drive icon on the desktop (often it's named 'Macintosh HD') and then click the Command and 'I' button at the same time to 'Get Info'. With a 1TB drive (1000GB), there would always be plenty of room for backups.

So a 500GB drive could backup to another 500GB drive, but as the amount of data on the drive increased, there would be less room for backups on the external drive. However, keep in mind the amount of data on the drive can easily increase so I just go by a rule of thumb and get a backup drive that is at least twice as large as the drive capacity of the drive you are backing up. For instance, if your internal hard drive is 500GB and you are using 250GB of on the drive, the minimum size drive you'd want to backup to is a 500GB drive. Generally you want a drive that is at least twice as large as the amount of data you are backing up.

Time Machine works great with external USB or Firewire hard drives. The first thing you'll need to use Time Machine to backup your Mac is a second hard drive.

Seagate external hard drive time machine