Some questions about backing up MacOS

Guy Burns wrote:

What I'm trying to understand is how I backup MacOS and third-party software, now that Disk Utility or CCC can't do it.

Technically CCC can clone an entire macOS boot drive of an Intel Mac, but you must erase the destination volume and enable "Legacy" mode in CCC. So it is not quite the same as pre-Catalina, but it is still sort of possible. This is no longer a good option for M-series Macs due to the new concept of "Ownership".

It is no longer possible to restore the whole system using a Time Machine backup, as the signed system volume is not backed up. Non-core applications and user data can be restored in full using Migration Assistant, preceded by a system reinstall if necessary.

Ques 4

I want to fully understand the above statement. There appears to be a "protected" part of the drive on which MacOS resides, that cannot be accessed by anyone other than Apple itself. It's untouchable. As long as the drive is correctly functioning, and you don't wish to upgrade, MacOS will never need to be restored or recovered.

Correct?

Here is an Apple article regarding the new drive layout with the signed & sealed system volume:

Signed system volume security - Apple Support

If anything corrupts the sealed system volume, then the system will not boot since it may mean the system is potentially compromised. A person can break the seal from Recovery Mode or while booted from external media (assuming the Intel Mac's security settings have been modified to allow booting from USB). With normal use and barring a hardware failure, or file system corruption, then yes.

Ques 5

However, if the "protected" part gets hit by a stray gamma ray, for instance, and MacOS is corrupted…

Q5A:• How do you recover/restore MacOS – only via the internet?

It depends. For an M-series Mac you can boot from a macOS USB installer. Same for a 2017 or earlier Intel Mac.

With a 2018-2020 Intel Mac with a T2 security chip, then again it depends. A T2 Mac by default does not allow booting from USB, however, as long as an admin macOS user account still exists on the internal macOS SSD and you can authenticate to the T2 chip with the admin user account, then maybe you could enable booting from USB. I say maybe because sometimes the T2 chip gets confused/corrupted and doesn't recognize the admin user credentials. Don't rely on USB boot being available on a T2 Mac.

Q5B:• Can I use the original installer that I saved?

See answer to Q5A.

Q5C:• Can it be recovered from a Recovery partition?

Possibly, but again it depends on what caused the problem. The Recovery partition (actually a recovery volume now) is not signed & sealed AFAIK (I've never seen any documentation about that).

Ques 6 – Recovery Partition

I have never used a Recovery Partition. If one was installed in Mavericks, I removed it long ago. I had no need of it because of my whole-system disk-image files. But as regards Monterey and Ventura…

Is there a hidden Recovery Partition for both of those, or has that gone as well?

If you used CCC to back up the complete system on Mavericks, then it may have also backed up the hidden Recovery partition (sometimes you had to confirm to CCC to do this). If you had CCC create a DMG of the complete system and it also backed up the recovery partition, then when you restore using CCC, CCC will automatically recreate the recovery partition.

With macOS 10.15+, the Recovery partition is actually now another hidden APFS volume. AFAIK, it is only accessible for booting by using Command + R since the Recovery partition has not been visible as a separate boot option for a while now.

FYI, a bit off topic, but this may be of interest to you if you want to dual boot an Intel Mac with macOS 10.13+ which uses the APFS file system and an older version of macOS 10.11 or earlier which does not understand/recognize the APFS file system. You can use rEFInd which is a graphical boot manager to easily switch between the older & newer OS. rEFInd is a shell script that places its boot files onto the hidden EFI partition so nothing of rEFInd is actually running in the OS after the script finishes its installation of rEFInd. rEFInd can also see the hidden Recovery partitions/volumes as well.

Continued....

Select a Local Snapshot

Select the local snapshot you want to roll back to

[Problem with terminology: I didn't set up a "local snapshot". I was in Time Machine and I clicked

on "Back up now" – a once only, 10GB capture.]

With systems using the APFS file system, TM and other backup software such as CCC take advantage of one of the key features of the APFS file system which is the ability of taking a snapshot of the APFS volume very quickly. In addition, TM keeps some of these local APFS snapshots around so you can have much faster restoration of data if the data is contained in that snapshot. Plus if you don't have your TM backup drive handy, you may have access to some recent backups.

View APFS snapshots in Disk Utility on Mac - Apple Support

Anyway, I chose the only snapshot there, dated "16 Nov 2024, MacOS 12.7.6" and I received the reply: "Are you sure you want to roll back Monterey to it's state…"

[Problem with terminology – this is telling me that Monterey is going to be rolled back, but that's not the case. It will only roll back third-party software on the disk called "Monterey"]

The end result was what it should have been – the software I deleted was restored.

One of the downsides of naming your volume "Monterey".

SUMMATION 2

Correct me if I'm wrong:

No wonder this stuff is difficult to follow. What a confusing workflow and a mess of terminology.

I don't use TM so I cannot say. However, it is always best to experiment on a system before you put it into production to understand how everything works so when the day comes where you need to restore, you will have a better understanding of the process and any limitations.

I'll leave the other TM explanations to others with more experience.

Ques 9

Are OS installers dedicated for a particular type of machine? Meaning, if I have an installer that came from Apple for my 2013 iMac, should that installer be used for a Mac Mini? I've done so, and it works, but I've been wondering, is that desirable?

A macOS installer will work with all supported hardware. The only possible exception is for any hardware that was released after that particular point version of the installer you have. For example, if you have an installer for macOS vX.0, but you have a newer Mac model that shipped with and is compatible with vX.2, then your vX.0 installer won't work for that Mac....you would need to get the vX.2+ version of the installer.

FYI, the macOS 11.x+ installers are the same for both Intel & M-series Macs so a bootable macOS 11.x+ USB installer created on either platform will also work on the other platform within the limitation I outlined previously.

Others will be able to provide more details, but my quick answers to your Summation are:

Summation

• Gone are the days of creating a disk image of an entire disk, and being able to restore from that disk image.
  • See my comment below regarding CCC & TM.
  • You can still image & restore a data disk or data Volume.

• Gone are the days of using CCC or Time Machine to restore an OS.

Those days are gone for CCC. TM can restore the full system (OS, apps & data) but I don't believe you can select the OS by itself.



• Since sometime after Catalina, you have to use a combination of Time Machine, Migration Assistant, and the internet to restore an OS. Or is there an easier way?
  • Restoring macOS should be done via Recovery or Internet Recovery

Nothing wrong with rEFInd - but I'm not sure you really need it for this scenario. I've got a 2017 MBP running dual-boot Ventura and Sierra, and the built in firmware bootpicker has never had a problem recognizing both partitions and offering them.

Also have a 2012 MBP running Catalina, and at one point a few months ago had Snow Leopard, Mountain Lion, El Capitan and Catalina all on it - again, the firmware bootpicker had no issues and offered all four partitions for boot when holding Option.

g_wolfman wrote:

Nothing wrong with rEFInd - but I'm not sure you really need it for this scenario. I've got a 2017 MBP running dual-boot Ventura and Sierra, and the built in firmware bootpicker has never had a problem recognizing both partitions and offering them.

Yes, that is true. macOS 10.12+ can recognize APFS bootable volumes just fine so switching is a bit easier, but I still find it inconvenient if I'm always switching between them...its even nice when only needing the other OS on rare occasions. Occasionally switching to another boot volume it is fine, as is Option Booting, but rEFInd does make it so much easier. I only thought of it when the OP mentioned Mavericks and the local hidden Recovery Partitions.

Also have a 2012 MBP running Catalina, and at one point a few months ago had Snow Leopard, Mountain Lion, El Capitan and Catalina all on it - again, the firmware bootpicker had no issues and offered all four partitions for boot when holding Option.

Yes, Option Booting allows you to see all the bootable volumes, however, it is nice if you just reboot & have a menu where you can select any OS you want, or let it boot the default OS of your choice....all without having to remember to hold the Option key or change the Startup Disk setting which then becomes locked to the other OS .

When I was dual booting (even triple booted years ago, ugh!) it was really nice to have all options presented for a few seconds. Plus if you do want to boot into a specific local recovery mode volume, it is only possible with a utility like rEFInd. If you hold Command + R which of the various local recovery mode volumes will the system select? You think you know the answer, but what if that other OS is unable to boot, how can you select its recovery mode volume when dual booting? Or if the PRAM was reset? rEFInd can just make all of this easier.

That's good to hear. Glad we could help you.