Please check " Encrypt Backup Disk" and select " Use as Backup Disk". Generally, when connected successfully, a pop-up will appear, asking you whether to use the drive to back up with Time Machine or not. Connect the external hard drive with your Mac firmly, making sure your Mac can detect the external hard drive. You can backup Mac to external hard drive with Time Machine if you want to restore your Mac with the backup later. The old backup files will be deleted when the storage is full. Time Machine is the built-in feature on Mac for users to backup files hourly for the last 24 hours. Backup Mac to External Hard Drive with Time Machine
Most important of all, you need to be clear where the target files are. It is quite easy and simple to copy and paste files from Mac to the external hard drive, but it takes a long time and needs your patient. Basically, you can do it by copying & pasting files one-by-one from Mac to the external hard drive. It is much wiser to back up single files from Mac to external hard drive, because whenever you need a file, you can check out it from the external hard drive right away. Backup Selected Files from Mac to External Hard Drive Backup Mac to External Hard Drive with Time Machine (Strongly Recommended) Part 1. Backup Selected Files from Mac to External Hard Drive Part 2.
If you don’t know how to do it, follow the guide below: Quick Navigation Part 1. Sum it up, no matter for what reason, you need to backup your Mac to external hard drive.
After then, you can delete them from the Mac permanently because the Mac will never belong to you any more.
Whether you’re using MacBook Pro or iMac,instead of buying a Mac with more storage, it is cost-efficient to using external hard drives to back up files from Mac. Who knows whether the file will be deleted intentionally or unintentionally on your Mac, or your macOS crash accidently. Taking the file security into consideration, it is always right to keep at least 2 copies of a file.There are multiple reasons for you to backup mac to external hard drives, either for file security, saving space or keeping privacy: Updated to macOS Data Recovery Tips by Harper on Feb 21, 2022