Can you bring back to life a bootable Mac installation if you have all the files?

[arsradu]

Hi guys,

 

So...trying to clean up Catalina, I ended up reinstalling Catalina over my Mojave partition...

 

Luckily, MacOS makes a Previous Content folder, and put everything I had on that partition in that folder. All the apps, all the user files, everything is already there.

 

Question is...can I put back all my files from that backup and make it boot back again as Mojave, instead of Catalina? I think it's only a matter of setting the right permissions. But no matter how hard I tried, I couldn't get it to show up in the boot picker of Clover. So...looks like it's not bootable...

 

Any idea how to fix this?

 

Last option would be a fresh install... But since all the files are already there, I'm hoping maybe there's a way to actually use those instead, so I don't have to reinstall everything back from scratch.

Edited August 11, 2019 by arsradu

[arsradu]

I've managed to put back Mojave. First on a different partition, then on the initial partition. The problem is that, it's not MY Mojave. And simply copy pasting (or even cloning) all those files back into the original location doesn't seem to work either.
But yeah, initially it would not let me downgrade from Catalina. And I Couldn't simply keep Catalina due to a keyboard issue preventing me to login.

So now I either find a way to put back those files the way they were, oor...move on and simply make a clean install and reinstall everything from scratch. I can still salvage some files that are not critical for boot, but I thought maybe I can make it boot again, given that all the files seem to be already present.


 

Edited August 11, 2019 by arsradu

[arsradu]

2 hours ago, Hervé said:

Well once you're back on your feet (and I highly recommend a clean fresh re-install), do consider making a backup image of your Mojave partition so that, if it ever was required again, you may re-install things exactly as they were. There are cloning apps fo that or you can use macOS own imaging facility available in Disk Utility. You'd have to boot from your USB installer to do this of course (or from another installation/partition, say, Catalina).

 

Thanks, Herve.

 

That's pretty much what I ended up doing... Clean install, I just finished installing most of my apps. And I was considering buying maybe another HDD for a Time Machine backup. Thing is, I do have plenty of space on one of my hard drives. Problem is....Time Machine requires a full HDD, even if the size of the actual backup is a lot smaller than the size of the disk. And I don't have that available right now.

 

I've never used the Imaging feature you are talking about from Disk Utility... But the thing is...I didn't think it will end up so badly. So I didn't make a backup. But with Catalina's "-data" partition, things are now confusing as hell. I still don't understand how that's supposed to work. Anyway, a Time Machine backup would probably be the best choice here, since that's automatic. But yeah, I need to get a dedicated HDD for that. Which, right now, sounds like a really good idea. :))

 

Update: Nevermind. Apparently you can use a partition on a disk, for backup, with Time Machine. Doesn't have to be an entire disk. I don't know why I thought you needed an entire disk for that. Well then. Backing up now.  

 

Update2: So this is new to me. It looks like the secret to a small Time Machine backup is excluding external drives. By default Time Machine seems to make a backup of absolutely EVERYTHING! And when I say everything, I really mean EVERYTHING on your computer. Including stuff from other HDDs! So, if you only want a backup of your main system, you need to exclude everything else manually.

Initially I thought it will just backup the SSD you're booting off of, to a separate location. But that's not the case. It takes all the data, from all the partitions and tries to squeeze it into a single place. Which...depending how much data you have, might not even allow you to complete that backup (like in my case, it would show up as "insufficient space" although there was plenty available). According to my calculations, of course. :)) Which, in this case, were wrong.

The second I excluded external drives from that backup, the size of the space necessary to complete the backup dropped from 600GB to about 30GB.

And yes, of course, with time, the backup space will fill in. But i don't need to backup everything since years ago!!! I just need a backup plan to recover the OS, in case stuff like the misadventure I had yesterday happens. And for that, a few hundreds of GB of space on a spare partition, should be quite enough. I guess time will tell. But so far so good!

Edited August 11, 2019 by arsradu