Adding drive to Mac Mini M4

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Adding drive to Mac Mini M4

I have a Mac Mini M4. I did not get a Mac with enough memory, so I want to add an additional drive (SSD). It will attach like an external drive, but be permanently attached. Can I do this and have it be seen by the Mac as an additional drive rather than a backup drive? In a PC the main drive would be "C" and additional drives might be a "D" or "E" drive. I would want to be able to back up the integral as well as external drive to another removable backup drive. Can I do that with the Time Machine. In each case I am looking for directions on how to do this.

Mac mini, macOS 15.6

Posted on Oct 26, 2025 5:47 PM

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Answer 1

Top-ranking reply

den.thed

Level 10

90,706 points

Oct 26, 2025 6:51 PM in response to PV84DP91

Yes you can use an external SSD to gain storage space, but forget everything you know about windows drives.

Erase and Format the external SSD "GUID Partition Map / APFS" using the following instructions.

Erase and reformat a storage device in Disk Utility on Mac - Apple Support

Move your larger Photos, Music, Movie Libraries to that external SSD.

Move your Photos library to save space on your Mac - Apple Support

Change where your music files are stored on Mac - Apple Support

Move your iMovie for Mac library - Apple Support

Then use a second larger HDD or SSD for Time Machine backups.

By default Time Machine backups the Mac mini's internal SSD and the libraries on the external SSD.

Back up your Mac with Time Machine - Apple Support

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Answer 2

John Galt

Level 10

155,060 points

Oct 26, 2025 6:33 PM in response to PV84DP91

Connect and use other storage devices with Mac - Apple Support

Can I do that with the Time Machine.

Time Machine backup devices are for Time Machine's exclusive use, so if you need additional storage, purchase one drive for external storage purposes and another one for Time Machine backups.

You can have as many of each as you wish... they are not limited to only the 26 letters of the English alphabet. If you require more drives than the Mac has USB ports, use a powered hub.

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Answer 3

Oct 27, 2025 2:51 AM in response to PV84DP91

Don't be tempted to go for "superfast" highly expensive drives unless you are happy to spend large sums unnecessarily.

The "best" all round bargains are NVMe SSDs from named makers like Crucial, Kingston, SanDisk, Integral etc. fitted into USB-C enclosures.

You can get 2TB versions for around £100 on Amazon together with another £15 for an enclosure.

Thunderbolt enclosures are available but cost at least 4 times more and give a doubling of the speed but in every day life this is quite unnoticeable unless you are spending all day copying hundreds of gigabytes of files.

Finally, you never get the speeds advertised so take them with a pinch of salt especially as they have little or no effect on the performance of your Mac.

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Answer 4

Old Toad

Level 10

215,196 points

Oct 28, 2025 3:22 PM in response to PV84DP91

Look at the 1.0TB OWC Envoy USB 3.2 (10Gb/s) Bus-Powered Portable NVMe SSD. It also comes in 2TB size.

It's very fast:

OWC is considered the premier hardware supplier for Macs by most of the experienced users here.

Just some food for thought.

If budget is a concern consider the following setup:

I have four of them with my M4 Mini but the OWC Envoy is not that much more expensive and twice as fast.

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