Inherit Time Machine Back Up After clean install

[dsaponaro]

In order to upgrade from Monterey to Ventura I recently wiped my iMac and did a clean install. Can anyone walk me through the process of picking up my previous Time Machine back up where I left off before the upgrade? As of now, when I plug in my external drive I can browse the previous back ups or start a new back up from this point on But would really like to just continue on while not loosening my previous year of back ups. Hope that makes sense?

I seem to recall this happening last year as well when upgrading. And believe in older versions of the OS was given the option to inherit a previous backup and continue on when upgrading but Apple removed this option? I think last year I plugged in the drive and entered something into the terminal to get it working properly.

Honestly I’m not all that familiar with the terminal so I’m a bit leary messing with it. Can anyone help?

Much thanks in advance.

 

[hoo-man-b-ing]

I recently did a clean reinstall of Ventura on my Mac and when I connected Time Machine to the encrypted backup, it asked me if I wanted to overwrite it or continue to add to it (I don’t recall the exact prompt.)

I chose to continue to use it and it’s exactly what I expected — all of the previous files/versions are there and so are the new ones from my current backup. I didn’t do anything in Terminal.

An honest example of “it just works.” 🤓

 

[dsaponaro]

I recently did a clean reinstall of Ventura on my Mac and when I connected Time Machine to the encrypted backup, it asked me if I wanted to overwrite it or continue to add to it (I don’t recall the exact prompt.)

I chose to continue to use it and it’s exactly what I expected — all of the previous files/versions are there and so are the new ones from my current backup. I didn’t do anything in Terminal.

An honest example of “it just works.” 🤓

Thanks for the reply.

Hmmmm…. I don’t seem to get that option. Only choice I have is after plugging in my TM Drive under Time Machine in general settings I see “Add Backup Disk…”. When I click on that a window pops up showing me my drive with available space if I select that and then click ”Set Up Disk…” it starts the countdown for a back up. I stop it before it actually starts because I want to be sure it will “continue“ my back ups and not start a whole new one.

I guess my question is will this start a whole new TM back up of my system or continue from my previous backups so I have access to all the previous months of data etc… continuously? Not in separate sessions.

Thanks again!

 

[Alameda]

Can anyone else offer any further insight?

To be honest, I think you would be much better off starting a fresh Time Machine backup. If needed, buy another drive (they’re cheap) and use your old backup in case you want to pull off some old file one day… which you’ll never do.

But I’ve had Time Machine backups corrupt after a few years and OS updates, and they begin to take forever and ever to run, so this might be an ideal time for you to set up a fresh backup. That is what I would do, anyway.

 

[dsaponaro]

To be honest, I think you would be much better off starting a fresh Time Machine backup. If needed, buy another drive (they’re cheap) and use your old backup in case you want to pull off some old file one day… which you’ll never do.

But I’ve had Time Machine backups corrupt after a few years and OS updates, and they begin to take forever and ever to run, so this might be an ideal time for you to set up a fresh backup. That is what I would do, anyway.

Thanks for the reply. Yes, that is an option but not really ideal either. While HD’s are relatively cheap I don’t want to have to go out and purchase one every time I do a clean install.

For the sake of problem solving how does one re-associate a previous Time Machine backup with a clean install of an upgraded OS so as it doesn’t start an entirely new back up “state” and simply continues where it left off only backing up files that have changed?

The option use to exist. If it still does then it’s either worded incredibly bad when plugging In the disk after the new OS install or it’s no longer an option. Leaving only the option to create an entirely new back up point.

On another note I find it interesting you mention “they take forever and ever to run”. Do you mean to run the back up or access a previous backup? Reason I ask is that while I’ve never really noticed back ups taking forever to run I have noticed (since the last few OS versions anyway) it takes forever to access files from previous backups on my drive. Navigating through the Time Machine interface is excruciating speed wise etc…. Clicking on the time line often has unbearable lag and can sometime take 30 seconds to a couple minutes for the files to update and appear in windows etc…

I seem to recall this being an issue with Monterey maybe? Remember reading about quite a bit after the OS was released and seemed to be a common problem that has never been addressed? Curious if I was to wipe the drive and start a new backup from scratch if it’d be smooth as butter?

 

[okkibs]

The issue might be that you did a clean install instead of upgrading. I usually do clean installs as well and never got the option to continue the backup either. You can stop doing clean installs in the future though, only one from Big Sur onwards is necessary to get rid of legacy kernel extensions and that's it.

Nowadays MacOS is running from an unchangeable snapshot so there just isn't anything a clean install could clean out anymore. All the extra data generated is now stored on a separate volume, you can find that under /System/Volumes/Data (browse to it with Finder->menubar->go->go to folder, it will say it's "Macintosh HD" but it's actually not. You know it's the right volume when it shows the folder "macOS Install Data" which contains some MacOS update files.

This volume stores literally everything you generate on your internal harddrive, so for example your entire user folder sits on there as well as the apps you download in addition to the default apps. And if you download a MacOS update it's downloaded to that volume since the actual MacOS volume cannot be modified (when the actual update starts, it unlocks the MacOS volume and locks it afterwards again).

When upgrading to a newer MacOS the actual MacOS is replaced completely with the new one and is always clean installed on a separate volume. So whether you upgrade or do a clean install, the actual MacOS that boots in the end will be exactly the same. As in, bit for bit it will be the same. Apple actually provides a cryptographic hash (the "seal") that is verified to make sure your MacOS installation is the same as everyone else's. If just a single bit on any MacOS file differs, MacOS cannot start up as it must have been damaged.

This makes it almost impossible to modify MacOS from a clean install and have it still boot up. So no software can damage MacOS with a driver installation gone wrong anymore. When you use the factory reset option on a new ASi Mac it actually just wipes the extra volume and doesn't change the MacOS volume in any way.

 

[Kontikonsumi]

Hey everyone; are there furthe rinsights to this? I run into the same problem (clean install and somehow want to reliably use the old TM backups, without buying a new drive for the new TM-backup).

 

[ThrowerGB]

I'm not sure I understand your problem. After wiping your iMac, how did you restore everything in your Users and Applications directories? If you restored from TM, then shouldn't any the system recognize itself and just then start adding new files to the TM backups?
I have had a similar problem a number of years ago, the TM backups themselves started showing a problem, which I wanted to fix by replacing the TM external drive. However when I'd copy from the old TM backup drive to the new one. It would start a new set of TM backups instead of appending to the old ones.
I eventually solved this problem by using Disk Utility to make an image of the old backup drive. Then use Disk Utility to unpack the image onto the new TM drive. Of course one needs a place to store the image (which itself is large). I can't remember where I stored it during the process, perhaps on a 2nd external drive with enough space.

 

[jagooch]

I recently did a clean reinstall of Ventura on my Mac and when I connected Time Machine to the encrypted backup, it asked me if I wanted to overwrite it or continue to add to it (I don’t recall the exact prompt.)

I chose to continue to use it and it’s exactly what I expected — all of the previous files/versions are there and so are the new ones from my current backup. I didn’t do anything in Terminal.

An honest example of “it just works.” 🤓

Odd. I erased my Macbook today, and reconnected the network time machine backup to it after the first login. I only want to restore certain files and settings, which is why I didn’t do a full restore.

I got the option and selected to continue to use it. However, when I enter time machine, it only shows files from today and that is
it! So much for resuming.

Luckily, I also backed up to backblaze so I didn’t lose my data. I just have to wait many hours to restore around 1.7 TB of data!

Apple needs to do better when it comes to Time Machine backup and restore.

 

[Brian33]

I got the option and selected to continue to use it. However, when I enter time machine, it only shows files from today and that is
it! So much for resuming.

I think those old files are still there. If I remember correctly, TM is odd and doesn't normally show files that came from drives (actually volumes) that aren't currently connected to the Mac. (After your erase, the new volume has a different UUID from the old one.)

I think you could access non-connected drives' files by pressing Shift-Cmd-C in the TM interface. That's the Finder shortcut for Go>Computer. IIRC it would then show the old drives (somewhere) in the interface so you could select them.

 

[jagooch]

I think those old files are still there. If I remember correctly, TM is odd and doesn't normally show files that came from drives (actually volumes) that aren't currently connected to the Mac. (After your erase, the new volume has a different UUID from the old one.)

I think you could access non-connected drives' files by pressing Shift-Cmd-C in the TM interface. That's the Finder shortcut for Go>Computer. IIRC it would then show the old drives (somewhere) in the interface so you could select them.

Maybe. I deleted the TM backup and started fresh by backing up to a new USB drive I purchased.

We may never know if there was a way to recover file from the now-deleted TM backup.