Moving to smaller boot drive,...Mojave to Monterey!

I’m upgrading from an old 13" Mid-2012 MacBook Pro that runs Mojave on an aftermarket (Adata) internal 960 GB SSD. The replacement is a 13" M1 MacBook Pro with a 512 GB SSD. I’ve cleaned up the old drive as much as I can, but it still has about 590 GB of things I want to keep access to. I’ve purchased a 2 TB external Thunderbolt drive (OWC Envoy Express) to help resolve the issue, but I could use some guidance on the best way to proceed. Should I just back up the current drive to the Envoy and use it as the boot drive? I’d rather use the internal drive as the boot drive and keep my music and photo libraries (about 300 GB total) on the external. How practical is this? If it doesn’t require getting too deep into the arcane innards of the modern Mac OS, how best to proceed?

And should I try to move one step at a time from Mojave to Catalina to Big Sur to Monterey, or attempt it in a single bound? Your thoughts (and prayers) are much appreciated! :grimacing:

How about both? Start by setting up the external as the initial boot drive and make sure you migrate all your old stuff to that external drive. Then, once you see the migration to your new Mac is complete and good, set up a new boot system on the internal flash storage and use MA to migrate everything from the external except for music and photos. Finally, on your internal system symlink to the external locations for that material. Should work just fine and be pretty transparent even with apps like Music and Photos that expect this stuff in certain locations in ~/. This would keep your internal lean, but still gives you access to all your media when the external is connected without much shenanigans.

I’d update all the way in one step. I don’t see any substantial advantage to doing it one major revision at a time. It’s just a lot of extra work and time.

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I had a similar quandary as I purchased a M1 Mini with 256GB SSD. I too ended up with an Envoy Express with an additional 500 GB SSD. Here’s what I did for what it may be worth.

I tried the “move the photos and music libraries to the external disk configuration” before and it worked OK. This time around I decided to move my entire home directory (using ditto) for my day-to-day non-admin account to the external SSD, then using the advanced properties in the Users pref pane to repoint the account home directory to its new location. My music and Photos library followed it to the external drive. The Envoy Express SSD is plenty fast enough for what I do (some light Arduino and XCode/iOS development, some Virtual machines).

I always keep the default admin account on the boot disk.

Time Machine is configured to another external USB drive, and backs up the boot disk and the Envoy SSD.

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Technogeezer, I like your plan; I’d love to hear more detail about your process for moving the home directory of your non-admin account to the external drive. Does it require setting up symlinks on the internal drive to point to the new location on the Envoy?

Simon, one giant leap to Monterey it is. I formatted the Envoy and installed a new system today. I’m a newbie at symlinks… but It looks doable. Thanks.

No. Symlinks are not recommended for account home directories.

Here is the process I use via a separate administrative account .
• Create a full backup of the existing system. This is just insurance.
• Note the UID of the user account to be moved.
• Connect and format the new external drive as APFS.
• Create a volume with for example, Home as a name.
• Create and run a Carbon Copy Cloner task with selective copy of just the selected home directory to the new Home volume.
• Enable permissions on the new Home volume using Get Info.
• Go to System Preferences > Users & Groups.
• Unlock the preference pane as required.
• Right Click (Control Click) on the subject user and then click on Advanced Options.
• For Home Directory:, choose the new external copy of the user home directory.
• For User ID:, use the UID of the new external copy of the user home directory.
• Exit System Preferences and Restart.

I has been my experience that this configuration survives in-place macOS upgrades. For migrating to a new installation of macOS as might be done for replacement hardware, this procedure applies after initial creation of a ‘stub’ user account. Nota bene - I have always created a separate administrative account as the first account (UID 501) and then created the active User account(s). Matching the User account definition with the existing cloned home directory then causes no conflict.

Symlinks to separate external media volumes for Movies, Music, and Pictures folders are independent of the location of the User home directory. If they were created and usable before the above procedure, they remain usable after as well. Since creation of symlinks to folders on external volumes is a bit fussy and may involve SIP, I was especially pleased that I could swap in a new mini configured with Monterey with zero account changes except home directory changes as defined above.


If you search this board, you’ll find instructions how to properly link to external media folders for use with Music/iTunes and Photos.

This is for the most part what I did, so I can confirm that it works without symlinks. My account was created on the boot disk to begin with, so I did not have to deal with UID settings. And I’m comfortable with UNIX shells so I used “ditto” instead of CCC.
+1 for keeping an admin account on the boot disk, in case the external is disconnected for any reason.

I also made sure that permissions were enabled on the external disk. You may not want to do this but I’m a stickler on limiting permissions to things for security reasons. Just make sure if you do enable permissions that there’s proper access to the home directory. I used the root and /Users disk permissions as a guide.

I had best luck with this when using a TB external disk. macOS treats is as a non-removable disk. I found when you try this with USB disks (haven’t tried it on Monterey though) you’re dependent on the disk getting mounted on a timely basis at login. I found that some times that didn’t happen and the home directory got placed back on the boot disk and “all my files were gone”.

Certainly you can use Apple documented procedures for moving Music media files and Photos Libraries to an alternate location should you not want to go all in on moving the home directory. No symlinks required!

Thanks for the reminder. I have added the appropriate step to my process above. I have yet to comprehend why permissions disabled is the default for new volumes. I have yet to find a good reason to disable permissions by default. This has plagued me for years.

I decided the best way to keep it simple would be using Migration Assistant to import everything into the new install of Monterey on the Envoy drive, make sure everything works as expected, then remove the music and photos, clone the now much smaller drive to the 512GB internal and point the media apps to the folders in the external Envoy drive. I’m a longtime Super Duper user, so my clones and backups are made using their current version.
The first part is almost working “as expected” but… none of my iTunes local music was found! The new system is aware of the iCloud versions, but not the local ones, so I still need to hook that up before proceeding, it seems. I tried dropping the a copy of the whole iTunes folder into the new Music folder and restarting, but it wasn’t automatically found. As usual, suggestions are most welcome!

2 years ago I faced a similar issue. The only issue I had moving data from the boot drive to an external drive was in dealing with files managed by apps rather than just the Finder.

I determined that moving the contents of my Apple Music and TV libraries to an external hard drive would create enough free space on my new system that I would be comfortable with. I looked at the ‘Media folder location’ entry under the preferences for each app and then copied the portion of the hierarchy in the Home folder to the external drive. I then started the Music app and replaced the Home folder reference to the external drive. Unfortunately, at that point, I saw the media files being again copied from the Home folder to the media folder on the external drive, resulting in duplicate files.

I then searched for some outside help, via the book ‘Take Control of Your Media Apps’. A section of the book on using external drives gave a cookbook for letting the app populate the Media folder. Here are the steps from the book for populating the Music Media folder (populating the the TV folder works the same way:

“Go to Music > Preferences > Files.
If “Keep Music Media folder organized” is not checked, check it. (After you’ve moved your files, you can go back and uncheck this option if you so desire.)
In the “Music Media folder location” section of the Files preferences, click Change.
In the dialog that appears, navigate to your external disk or network volume. Continue navigating to where you want to keep your Music Media folder (this may be at the root level of the disk). Click New Folder, name this folder Music Media, and then click Open.
Click OK to save your changes.
Choose File > Library > Organize Library.
In the Organize Library dialog, select “Consolidate files” and then click OK.”

Excerpt From
Take Control of macOS Media Apps (1.5)
Kirk McElhearn
This material may be protected by copyright.

So I first erased the contents of the appropriate folders and followed the steps above. After doing a random check on some files (Pick a tune in the Music app, right-click on it, select ‘Show in Finder’, and confirm that the volume is the external drive),. After the verification was done, I backed up both the external drive and boot drive, let everything sit for a few days, and then got rid of the original media folder on the boot drive.

Followup note: I recently reduced my data on the boot drive by moving some more large collections, including the iCloud Photo Library to the external drive. This went smoothly, although the Photo Library took several days to successfully sync with the cloud version. Of course, I also needed to modify apps involved with referencing or managing the collects to point at the new locations of the active folders.

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