Restoring from Time Machine (2 drive system, new SSD)

[macstatic]

I've got a dual drive Mac Mini (late-2012) where the main hard drive has stopped working and I'm awaiting a 2TB SSD to replace it.
(by "dual drive" I mean a (small; 250 GB) SSD for MacOS and apps, and a (large; 2TB) HDD (soon an SSD to replace it) for the user accounts. Using the Mac Performance guide: Relocating the Home directory off the Boot drive instructions I've made this work well throughout the years and found it to be a great price/performance compromise.

I have a recent Time Machine backup (external USB hard drive) of the Mac Mini, but I've never totally restored a Mac using Time Machine before, and wonder how I should go ahead, and especially with a "non-standard" dual drive system like mine?
An estimated guess is something like this:

1) (after inserting the new, empty 2TB SSD in the mac), boot it up from the (small) SSD as usual (luckily, I think I created a test-user on that SSD before it crashed)
2) log into the user that's on the (small) SSD (obviously I can't log into the other user accounts as they're all on the failed HDD)
3) use Disk Utility to partition the (new, large) SSD (MacOS extended, Journaled) and give it the same name as before
4) create all the users that were on the (large) HDD before, taking care to have the same user names (and passwords too I believe, as otherwise I possibly can't access the restored data later on?)
5) Move those users from the (small) SSD to the (large) SSD as per the instructions in the link above
6) once tested working, restore all the user's files from the Time Machine backup (I've never done this before, so I'd be grateful for some pointers). Or should I NOT create the users first, but Time Machine does this by itself when restoring? And will Time Machine understand that the boot drive with MacOS on it is not the same as the user's drive?

Does this sound like the way to do it?
I'm on MacOS 10.13.6 (High Sierra).

 

[gilby101]

I am not convince by diglloyd's instructions. You shouldn't have need to manually move home directories, macOS should have done it when you specified the new location. So I don't know exactly what you did. Nevertheless...

Regarding your numbered points:

1. I hope the 'test-user' is an administrator.

3. Why not APFS? Same name is probably good.

4. Don't the users already exist in the small system disk? (with their home directory pointing to the failed drive). You might need to tell Users and Groups where the home directories are located (or maybe next step will do it for you).

5 & 6. I would attempt to use Migration Assistant to recover the user files (including settings) from TM backup to new disk.

You will need to experiment - choose the smallest (in terms of disk) user to recover first.

Only go the more cumbersome (error prone) process of new users and manually copying home folders if Migration Assistant doesn't work. If you do need to create new users, try and make sure they have the same User ID (the numbers from 501 upwards). This is what file permissions are based on. If UserIDs are different you will need to mess with file permissions at the end and you don't what to have to that! Same password doesn't matter.

 

[macstatic]

Thanks for your pointers. I'm looking forward to getting this done and working again 😅

I am not convince by diglloyd's instructions. You shouldn't have need to manually move home directories, macOS should have done it when you specified the new location. So I don't know exactly what you did. Nevertheless...

Is there a different way of doing this? Digilloyd seems to know what he's doing, and I've followed those instructions for several different Macs. But I'm open for improvements of course.
I just tried going to the "Users & Groups" system preference and create a new user, but there's no option for where to place that user.
It's only when you've already created a user that you can right-click on the user's name (in the "User's & Groups" system pref) and get to "Advanced options".
Is there a better way?

Regarding your numbered points:

1. I hope the 'test-user' is an administrator.

Yes, absolutely!

3. Why not APFS? Same name is probably good.

Good question. It's been a while since I had to reinstall everything, but I seem to recall staying away from AFPS because it had some issues and incompatibilities with something, and since I've been using HFS+ has worked in the past I just decided to keep using that. Why do you suggest I use APFS?

UPDATE: I looked through some old postings of mine and think I decided against APFS because of being warned that it shouldn't be used on the same partition/drive as where MacOS High Sierra is.
Now, this drive won't have MacOS on it, so maybe that no longer applies, but as the saying goes "if it works, don't fix it!" and it's already troubling enough to have to restore a backup and make everything working again.

4. Don't the users already exist in the small system disk? (with their home directory pointing to the failed drive). You might need to tell Users and Groups where the home directories are located (or maybe next step will do it for you).

Yes, I think that's where the user information is stored. I believe the login window still shows all the users even if the large drive isn't present, but of course if I try to log into one of them I won't get anywhere.
The exception being the "test user" which I didn't move to the large HDD but actually resides on the small boot SSD.

5 & 6. I would attempt to use Migration Assistant to recover the user files (including settings) from TM backup to new disk.

Does Migration assistant rely on finding a username already available, does it create it if it's not available when you try to recover its data, or does it do both?
In my mind I'm thinking that if I create all the users first (by using the "Users & Groups" system pref), then move them over to the large SSD, and from then on finally run Migration Assistant to restore the backup it will recognize the usernames and restore data to where it belongs...

You will need to experiment - choose the smallest (in terms of disk) user to recover first.

Only go the more cumbersome (error prone) process of new users and manually copying home folders if Migration Assistant doesn't work. If you do need to create new users, try and make sure they have the same User ID (the numbers from 501 upwards). This is what file permissions are based on. If UserIDs are different you will need to mess with file permissions at the end and you don't what to have to that! Same password doesn't matter.

Yes, messing around with file permissions isn't much fun, although an app such as BatChmod helps a lot (unfortunately the app's web page where I downloaded it from a while back doesn't work now, but here's some info from another page). I've used it to fix similar issues (it's always a huge pain though, and a relief when it's done. I've usually solved it by doing a "Get info" on the various folders of a working user on the same or different Mac to compare with).

So regarding the user ID: you're saying that if things should go smoothly I need the user ID of the user I've just created on the new drive (by using the "Users & Groups" system preference) to match the user ID of the Time Machine backup for that same username? How can I find the user ID of the backup?
I assume once I know the ID of the username on the backup I can go to "Users & Groups" again and right-click (Advanced options) in the user I created on the new/large SSD and change it to that number.

UPDATE: I just realized that prior to do anything at all (creating new users etc.) I should just log into the Mac using the "test user", go to the "Users & Groups" system preference and do a right-click (Advanced options) on the various users I already have from before! That should take care of figuring out the correct user IDs for each user which will match that of the backup.
So I guess the big question is how I should "link" the user-account login info (on the boot drive) to the various user accounts that I somehow need to recreate (on the large, new/empty SSD that I'm awaiting any day now).

 

[macstatic]

Here's an update since last posting....

I've successfully installed and initialized (MacOS extended, Journaled) the new 2TB SSD I received (to replace the broken 2TB hard drive), booted the Mac Mini up and logged into the "test-user" which resides on the smaller boot SSD. Worked fine as expected (because "test-user" is on that same drive).
Prior to doing anything else (and hence risking messing thing up) I went to the "Users & Groups" system preference, right-clicked on each of the users ("Advanced options") and did a screenshot of each one so that I could go back and check the user ID and other info if I need to do that later on.

Moving on.... Now for the other users (which were moved over to the larger HDD); they're no longer available as the broken HDD is of course gone, and the new SSD to replace it is empty, but the MacOS login window still shows them.
So I tried running Migration Assistant (while logged into "test-user") and sure enough all the accounts were on that backup, but it says "This user's home is relocated and will not be copied" as seen here:

I'm guessing this is because Migration Assistant is looking for users by those same names in the same location, but of course the new large SSD (yes, I made sure to give it the exact same name as the large HDD) doesn't contain any user folders at all.
So my next thought is that since Migration Assistant doesn't allow for restoring to what isn't already there I probably have a couple of choices:

1) delete the existing users (except for "test-user" of course!) within "Users & Groups", then create them again (from the same system preference) which of course creates those users from scratch and places them on the boot drive. Then move each user to the larger/new SSD.
Finally, run Migration Assistant again and see if it now will recognize the users by their same names as before and allow restoring. If not I might have to look up their user IDs from those screenshots, change them in "Advanced options" and try again.

2) try to boot into one of the users and see what happens.
So I tried this (with the least important user) and sure enough I was able to log into a user, but with several keychain errors and so on. I'm not sure if it was even properly created or just in RAM because there was no home folder to be found on either hard drive, so I logged out and once again logged into the "test-user" where I......
(within the Finder) created an empty folder with the name of the user, then I logged out of "test-user" and into that user's name again. This time I noticed that the folder I had created got filled up with those familier Home folder sub-folders (Desktop, Documents, Movies etc.).
So once again I tried restorting from Migration Assistant, but unfortunately this didn't help.
I also tried entering Time Machine from the menu-bar in order to try and restore one folder at a time, but it didn't show me any backups to choose from.

3) delete, re-create and move the users (as in step 1), then instead of using Migration Assistant I'd manually use Time Machine (from the menu-bar) to restore one folder at a time.

So before I risk messing things up badly, what do you suggest I do next?

 

[macstatic]

Success, finally!
After a lot of hair-pulling and trying all the hard ways to do this I finally figured out that the solution was easy-peasy! Read on.....
I searched for online info about the matter, but apparently just about everything is geared towards the usual single-drive system (where MacOS/apps and the user accounts are on the same drive, unlike mine).

What didn't work, that I tried was this:
Booting into "Recovery mode" by holding down the Option (ALT) button while booting, which allows you to select the drive to boot from (I understand you can also just hold down CMD and R while booting, which gets you directly into Recovery mode).
When done you get to choose from a few things: Disk Utility, Reinstall MacOS, Terminal etc. and what I tried here: Restore from Time Machine backup).
Indeed, it managed to restore the backup on to my new/empty SSD, but it only restored the boot drive along with its single user ("test-user"). So all of a sudden I had two boot drives, both with the same drive name!

I tried this a couple of times, and even tried booting from a bootable USB-thumbdrive with High Sierra (MacOS 10.13) on it. Neither made a difference, but gave the same result.
No wonder, because re-reading the description within the recovery mode menu it says: Restore from Time Machine backup -You have a backup of your system that you want to restore.

At this stage (as I felt I had tried just about everything) I was wondering if the solution would be to get my hands dirty and mess with stuff that could potentially cause some serious havoc (delete the existing users, create new ones and move them over to the new drive, change user IDs or UUIDs etc.), but having read several "how to restore from Time Machine" online guides decided to continue trying out all the standard ways of doing things first...


What did work was this:
Believe it or not, just restoring the normal way in Time Machine solved everything!
And I didn't have to "hack" or mess around in any non-standard way either.

Here's a complete step-by-step guide (especially for new readers who haven't followed the entire thread).

1) Start up the Mac as usual (remember, the boot drive is still OK, but contains just one user ("test-user") which is on that drive. The other users were all on the separate, larger HDD that is no longer working and replaced by a new/empty drive).
2) log into "test user" (which is physically on the same boot-drive and has administrator rights. I created this user before the hard drive crash for these kind of situations, and I'm very happy I did! I have no idea how I would solve these problems if the boot drive didn't have any user on it -if anyone knows, please share!
3) Check that the new/empty replacement drive has been initialized (I chose to go for the good old HFS+ for reasons I don't quite remember, but have been recommended that I do. Others might want to choose APFS)
...is available from the Mac Finder (desktop), and that it has the same name as before (if not, rename it -if you don't remember the exact name or spelling you can open up the most recent Time Machine backup folders from the Finder and see the folder-name which contains the users that reside on that drive).

4) Attach the external Time Machine drive if you haven't already. Go to the Time Machine icon in the menu-bar (or to System Preferences in the Apple-menu and select Time Machine there).
Be sure to turn off (disable) "Back up automatically" as we don't want it to create new backups now (I suppose it might confuse Time Machine, take a long time to do, probably be unnecessary as we haven't got any new files to back up and might even mess things up).
You may also have to select the Time Machine disk if it isn't already selected (press the "Select disk..." button).

5) If you haven't already done so, now is a good time to enhance the Finder windows by adding a "Path" button as this will allow you to faster and easier navigate on the drive in question.
So open up a Finder (desktop) window,
... then right-click in the top area (where the buttons are)
... and select "Customize toolbar":

6) Next, drag the "Path" icon to where you want it in the Finder window, then press the "Done" button:

7) Next, click on the Time Machine icon in the menu-bar (provided you've turned on the "Show Time Machine in menu bar" option as shown in the screenshot of step 4), then select "Enter Time Machine".

8) Having entered Time Machine you can now restore any individual file/folder. And as I found out; this also includes restoring an entire user's "home" folder!
I decided to try all of this with the least important Home-folder on that Mac, just in case something went wrong.

So, once having entered Time Machine which shows you a stack of folders...
... click on the "Path" button
... and navigate till you find the location of all your users
... then select the Home-folder of the first user you want to restore (don't open it, but just select (highlight) the actual home-folder as this will restore that user's entire Home-folder).
... choose the backup date you want to restore from (in my case I didn't want to risk using the very latest backup as I was worried it might have contained partly corrupted files because my hard drive was starting to malfunction, so I choose a day before that. Your mileage may vary as they say), then press the "Restore" button to restore it.
... You may need to select the path of where to restore it to (in which case you select the location on the new hard drive where that user's home folder was found).

9) When done, restart the Mac, and when you get to the login window, select the user you just restored and enter the same password as before.
After a while (it appears to rebuild caches or something because the first time after restoring it took longer than usual to open) you should be logged in as usual.
10) After having checked that everything is OK with that account, repeat the process with the other accounts to restore them as well.
11) Once all your account have been restored and checked OK you can enable (turn on) Time Machine backups again. My experience is that the first backup after restoring took several hours to do. I suppose it realized a new drive has been installed in the Mac with the user-accounts restored etc. and tries to catch up with all that.

I hope this helps someone in the same situation.
If anyone has comments to the above or further ideas for improvement, feel free to post here.