The new Mac Mini i4 at the time of this article is amazing value for one of the fastest machines on the market. However, upgrading the hard disk is quite cost prohibitive and can be solved with a fast Thunderbolt external Solid State Disk.

For example, all my photos in the Photos App are on my external drive. However, I found that permissions did not work as expected, chief being one user could see another user’s folders.

Simple Unix permissions are not sufficient and I wanted to carry over all the advanced ACL permissions too.

I finally got it working and here’s how I did it.

Confirming Your File System

This tutorial is written specifically for the Mac OS APFS (Apple File System) which is the default now for most Operating Systems. These instructions might also work with the prior generation HFS+ (Mac OS Extended) file system, but I’ve not tested.

Load up your terminal and use the diskutil info and you should see APFS,

The resulting output will say,

Purchasing a Fast External Hard Drive

I settled on an external Netac 2TB SDD (Solid State Disk) which was more than fast enough for my needs at 2000MB/s Read and 1700MB/s Write speeds interfacing with my Mac using USB 3.2 Gen 2.

Format the SDD Drive with Encryption

Though permissions will be setup, they can be bypassed with a different operating system. Encryption is the way to go, and has negligible impact to performance. However, don’t lose your password or key.

I prefer to encrypt my drive during formatting. And, I always format even brand new hard drives. You never know what can be hidden on there.

• Open Disk Utility (Command + Space, type "Disk Utility", press Enter).

• Select the external SSD.

• Click Erase.

• Choose:

  • Format: APFS (Encrypted)

  • Scheme: GUID Partition Map

• Set a strong password.

• Click Erase to apply encryption.

This uses XTS-AES-128 encryption with a 256-bit key, which is extremely strong. Without the password, even with advanced forensic tools, decryption is practically impossible.

As such, make sure you don’t forget your password or use an algorithm as I do.

Rsync Home Folder Over with All Permissions

Prepping Your System

I have different logins for the family which on the Mac OS show up as different folders under the “/Users”.

This command was tested with rsync version 3.4.1 protocol version 32 on Mac OS 15.6.1.

Create Your Folders

Log into a sudo enabled account and start your terminal.

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Verify it Worked

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Working Across Different Machines

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