Apple's Moves Point To a Future With No Bootable Backups, Says Developer

The ability to boot from an external drive on an Apple Silicon Mac may not be an option for much longer, with the creation and use of the drives apparently being phased out by Apple, according to developers of backup tools. Apple Insider reports: Mike Bombich, the founder of Bombich Software behind Carbon Copy Cloner, wrote in a May 19 blog post that the company will continue to make bootable backups for both Intel and Apple Silicon Macs, and will "continue to support that functionality as long as macOS supports it." However, with changes in the way a Mac functions with the introduction of Apple Silicon, the ability to use external booting could be limited, in part due to Apple's design decisions.

The first problem is with macOS Big Sur, as Apple made it so macOS resides on a "cryptographically sealed Signed System Volume," which could only be copied by Apple Software Restore. While CCC has experience with ASR, the tool was deemed to be imperfect, with it failing "with no explanation" and operating in a "very one-dimensional" way. The second snag was Apple Fabric, a storage system that uses per-file encryption keys. However, ASR didn't work for months until the release of macOS 11.3 restored it, but even then kernel panics ensued when cloning back to the original internal storage.

In December, Bombich spoke to Apple about ASR's reliability and was informed that Apple was working to resolve the problem. During the call, Apple's engineers also said that copying macOS system files was "not something that would be supportable in the future." "Many of us in the Mac community could see that this was the direction Apple was moving, and now we finally have confirmation," writes Bombich. "Especially since the introduction of APFS, Apple has been moving towards a lockdown of macOS system files, sacrificing some convenience for increased security." [...] While CCC won't drop the ability to copy the System folder, the tool is "going to continue to offer it with a best effort' approach." Meanwhile, for non-bootable data restoration, CCC's backups do still work with the macOS Migration Assistant, available when booting up a new Mac for the first time.

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