Carbon Copy Cloner’s 🤯 Blog Post on Bootable Backups

To be fair, that was a horrible movie. I wouldn’t wish watching it on my worst enemies:).

That’s possible, of course, but it would go against what they have explicitly told Mike Bombich about their future plans.

Of course, plans can change_ but I don’t know why they would have said it at all if they didn’t intend to do it.

I give it a 50/50 chance of working in macOS+1 (“Snow Big Sur”?)

I would not expect it to work in macOS+2.

Time will tell.



Ya….in about a week (WWDC).

Keep in mind that support for booting from an external drive and support for making bootable backups are not the same thing. Apple may well have decided to support booting from an external drive that has been set up fresh, from scratch while not supporting making bootable backups.


From that article…

A footnote at the very end of the document notes that, regardless of where the boot device is physically located, the boot process is always facilitated by a volume on the internal storage. The lightweight operating system on that volume (“iBoot”) evaluates the integrity of the boot assets and authenticates the OS on that external device, then proceeds with the boot process from that external device. What does all of that mean? In theory it means that Apple Silicon Macs cannot boot at all if the internal storage fails.

Given that Apple designs the entire chipset / architecture, it seems to me that this tiny little bit of boot code probably hardly ever changes. So it wouldn’t have to be tied to the internal storage as we think of it - or at least that it could theoretically be on a part of the internal storage that’s less susceptible to failure.

Kind of like a PC BIOS. If it goes poof you’d surely have a heck of a time booting.

We’d almost need to know whether the sorts of SSD errors we’re thinking of when we think “internal storage failure” (“wear”) would affect the part with the boot code.

It seems to me that that’s where they’ll likely land. Not allowing copies of the core OS files is a very useful security measure. But it would boggle my brain if there were no way to do a “from scratch” setup of an external drive on an M1 device.

blasphemy… the true Star Wars Trilogy is Ep III, IV, and V.

Nah, Rogue One, IV, V, VIII. :wink:. The best 4 Star Wars films

Geez, I’m NOT an engineer, but that sounds like something a TRILLION dollar company with a couple of hardware/software people hanging around the lunch room could design as a solution. Kinda like belts and suspenders. If this enclave thing craps the bed in the internal SSD, then the backup saved in the bowls of the M1 steps up.


And that said, we don’t know to what extent that isn’t already true. An Apple person talking about what happens to bootability “if the internal storage has died” could theoretically mean a number of different things.

Although if it’s not true that the storage for the boot code will outlast the rest of the internal storage device, that is indeed a Very Bad Thing.

Not to beat a dead (:wink:) horse but I’m thinking this SSD doesn’t need to be 1TB. Just large enough to contain what ever small amount of code (pin) is necessary to authenticate the boot process. And if something is creating a bootable backup (Carbon Copy/SuperDuper) that authentication code would also be on the external drive. Tim…are you listening?

I asked CCC support about this issue and Mike pointed back to the original article. To me the most relevant part was the sentence “If you were making your backups bootable in case of hardware failure, then that’s an extra logistical chore that you can now retire from your backup strategy.” I asked Mike what use other than for hardware failure could there be for a bootable backup. He stated that the bootable backups were used by developers for experimental purposes. Not being a developer myself, I didn’t know this, and now it all makes more sense. For the average user (like me) bootable backups are dead.

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Another, related but also slightly different use case is the anual game of, “What is the new version of macOS going to break for me?” Creating a bootable clone is pretty useful for that.