Help with erasing/formatting internal HDD on Mac Mini

Drive Partition and Format - El Capitan or Later

1. Restart the computer while holding down the Command and R keys.
2. Release the keys when you see the Apple logo and progress bar.
3. When the Utility Menu appears select Disk Utility and click on the Continue button.
4. After Disk Utility loads select the drive (out-dented entry with the mfgr.'s ID and size) from the side list.
5. Click on the Erase tab in the Disk Utility toolbar. A panel should drop down.
6. In the drop down panel set the partition scheme to GUID. Set the Format type to Mac OS Extended (Journaled.)
7. Click on the Apply button and click on the Done button when it is activated.
8. Once the above is done then you can proceed to partition the drive.
9. Quit Disk Utility.

If you try this but still get the same error, then that means that your HDD still has connections to your new startup drive. In that case, you will need to use the Terminal while still in the above procedure in order to force the HDD to unmount.

To use Time Machine you will need a separate backup drive formatted to use HFS+. This can be an HDD because speed is not that important for backups. The backup drive needs to be at least 2-3 times the size of the source drive. For a 250GB SSD, I would recommend a 1TB backup drive. These aren't too expensive. Visit OWC to see what your options are.

Your SSD can be formatted to use APFS, but Time Machine will not work with that format and should be formatted Mac OS Extended, Journaled.

Backups should always be made on a dedicated drive. If you have extra storage needs, then those also should be made on a separate drive. The Startup Drive should not be used for anything more than a startup drive.

Basic Backup

For some people, Time Machine will be more than adequate. Time Machine is part of OS X. There are three components:

1. A Time Machine preferences panel as part of System Preferences;
2. The Time Machine application located in the Applications folder. It is used to manage backups and to restore backups.
3. Time Machine requires a backup drive that is at least 2-3 times the capacity of the drive(s) it backs up.

Alternatively, get an external drive at least equal in size to the internal hard drive and make (and maintain) a bootable clone/backup. You can make a bootable clone using the Restore option of Disk Utility. You can also make and maintain clones with good backup software. My personal recommendations are (order is not significant):

• Carbon Copy Cloner
• Get Backup
• Deja Vu
• SuperDuper!

Visit The XLab FAQs and read the FAQ on backup and restore. Also, read How to Back Up and Restore Your Files. For help with using Time Machine visit Pondini's Time Machine FAQ for help with all things Time Machine.

Although you can buy a complete external drive system, you can also put one together if you are so inclined. It's relatively easy and only requires a Phillips head screwdriver (typically.) You can purchase hard drives separately. This gives you an opportunity to shop for the best prices on a hard drive of your choice. Reliable brands include Seagate, Hitachi, Western Digital, Toshiba, and Fujitsu. You can find reviews and benchmarks on many drives at Storage Review.

Enclosures for FireWire and USB are readily available. You can find only FireWire enclosures, only USB enclosures, and enclosures that feature multiple ports. I would stress getting enclosures that use the Oxford chipsets especially for Firewire drives (911, 921, 922, for example.) You can find enclosures at places such as;

• Cool Drives
• OWC
• WiebeTech
• Firewire Direct
• California Drives
• NewEgg

All you need do is remove a case cover, mount the hard drive in the enclosure and connect the cables, then re-attach the case cover. Usually, the only tool required is a small or medium Phillips screwdriver.