Migrating from a 27" iMac to M1 Mac mini


In May 2020, my late 2013 iMac 3 TB Fusion Drive failed.

With a limited budget, plus Take Control Books, I restarted my iMac with a fresh Catalina installation on a new external 512 GB SSD, plus a 1 TB SSD to establish new bootable, and backup scheme (using Carbon Copy Cloner, Chronosync). It’s the same period I realize that I could no longer rely on my 3 TB Apple Time Capsule to restore my iMac.

My current budget buys a Mac Mini 16 GB memory/512 GB SSD or 8 GB Memory/1 TB SSD. Wanting to take control, could I restart synching my 1.7 TB iCloud back up with a much smaller size SSD? Can I synch this iCloud with an external 4 TB HD, bought during my iMac failure crisis? Can I consider synching again on Big Sur? I just read the TidBITS Talk that I can’t reuse my iMac as a M1 monitor… I’ll arrange to remove the internal drives, and resell the 32 GB 1600 MHz DDR3 (4x8GB) memory sticks, etc.

In many ways, I find this situation very challenging.


In the past there have been published methods for setting up symlinks on your internal boot drive to locations on external drives to house large user data folders such as music, photos, or videos there. That allowed users to retain large data collections despite limited internal storage capacity. I never used such a setup myself and I’m by no means an expert on it. But I do feel like over the years I’ve read about a lot of potential trouble you can get into with such a setup because it after all remains inherently fragile. I would also imagine with the much more rigid file system footprint of Catalina and even more so Big Sur, this will become increasingly difficult or at the very least inconvenient. Like I said, I’m no expert here so you should definitely get other opinions, but I would be very reluctant to suggest going that route.

That said, if a large amount of your data is simply files you can store anywhere (i.e. apps don’t expect to find these files in certain specific locations), you could certainly choose to have those reside on a large external drive thus freeing up more limited (and expensive) internal storage. That should give you no trouble at all. Performance can be an issue, depending on types of files and workflow, but there are certainly decent performing external solutions available that don’t cost an arm and a leg.

I have been using soft links to external volumes for Movies, Music, and Pictures through several revision of OS X and macOS. I have successfully tested this on Big Sur but have not yet updated my production Mini to Big Sur because of schedule constraints.

The perceived fragility is real, but is mitigated by use of robust external connections such as Thunderbolt. The external drive containing the linked folders must be recognized at boot time to ensure proper mounting of the Volume containing the linked folders.

In my own experience Adobe Premiere, Apple Music, and Apple Photos work well with the soft-linked folders.

Symlinks are great to workaround an app that has hard-coded locations (e.g. your home directory) for data, but if it is possible to just point the app at another location, that’s even better.

Most of Apple’s apps (Music, Photos, etc.) will let you move the library to a new location and then tell the app (e.g. by holding down Option when launching it) to open the library from the new location. This is better than symlinks because the app actually knows about the new location.

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I have a 2019 27" iMac with a 1Tb Fusion drive. Boot time was ranging from 25 - 50 s and managing my large iPhoto library became very sluggish at times.
Changed to a bootable external SSD (Samsung 970 EVO 1Tb) in a Thunderbolt 3 enclosure (Total cost about $250, the enclosure is a bit over $100). Boottimes are now consistently in the 20 - 25 s range and managing the iPhoto Library is much more responsive. The Fusion drive is now a backup drive for the external SSD.

Hope this helps,

I like your solution, @marius.

And in case anybody is put off by the quoted $250 cost, let me just point out that you can get very similar performance (for all but a select few use cases) from a USB 3.1 Gen 2 case that’s far less expensive than the TB3 solution. TB3 is definitely better, but if money is an issue, people should know that they can still follow your idea for $120 shipped (plus tax). In fact I use this exact combo almost daily now and I’m very pleased.


$15 (with coupon)

Edit: and not to beat a dead horse, but the whole thing can in fact be accomplished for $100 if you instead opt for this less expensive Crucial SSD. https://www.amazon.com/dp/B078211KBB


Great points and if you go for the USB 3.1 Gen 2 case, a lower performance SSD is also perfectly acceptable as the bottleneck will be the USB bus and not the SSD.

I did try this set up and boot times on my machine were double vs. the TB3 setup, so I decided to shell out the extra bucks. For a data drive the USB option seems the best compromise between cost and performance.

Cheers, Marius