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CCC 5.1.27 and CCC 6 can make bootable backups on Intel and Apple Silicon Macs (11.3+) right now, and we'll continue to support that functionality as long as macOS supports it.

But as Apple's platform continues to evolve, we have to design our recovery strategies around the current hardware capabilities. A bootable external device may not be a part of that strategy. CCC can do so much more than just make copies of the system, and now is the right time to revisit your backup strategy and make it even better with some of the new features in CCC 6.

For decades, Mac users have taken for granted the Mac's "External Boot" feature. Prior to Mac OS X, people could simply drag and drop the System folder from one volume to another; presto, external boot volume. When Apple made it more complicated with Mac OS X, we pioneered the "bootable backup" solution (nearly 20 years ago!), and this has been a feature we've reliably supported on every new Mac and every new OS since then.

But Apple has never been afraid of shaking things up to blaze new trails. Big Sur and the new Apple Silicon Macs have shaken up the way Mac users will recover from hardware failure.

Big Sur's Big Change

All on its own, Big Sur introduced a significant new change to the creation of an external boot device. The operating system now resides on a cryptographically sealed "Signed System Volume" that can only be copied by an Apple-proprietary utility, "Apple Software Restore" (ASR). We were already familiar with ASR, so fairly quickly we were making bootable backups of Big Sur back in November. It hasn't been perfect though. We've performed tens of thousands of ASR clones at this point, and we've discovered that ASR is just not as robust as our own file copier. There are many scenarios where ASR simply fails with no explanation. ASR is also very one-dimensional; choosing to copy the system requires that we sacrifice other backup features, e.g. we cannot copy the system and retain versioned backups of your data, we can't evaluate what was copied, we can't exclude items from the initial backup, we can't save checksum data for later verification. So, while we're certainly able to make a bootable copy of the system with ASR, it starts to feel like using it causes us to lose sight of what's actually important to back up – your irreplaceable data.

Apple Software Restore isn't quite ready for the new Apple Silicon Mac storage

When Apple introduced Apple Silicon Macs, we discovered another snag. The "Apple Fabric" storage in these Macs offers per-file encryption keys (like the storage in iOS devices), and for months, ASR didn't work with it. Apple partially resolved that in macOS 11.3, but even now using ASR to clone the system back to the internal storage of these Macs doesn't... Read More

Update (July 16, 2020): Apple fixed the underlying OS issue described below in macOS 10.15.6, and the CCC 5.1.20 update puts our workaround on the back burner. Every challenge opens up new opportunities, and that's actually how we're seeing this incident in retrospect. Rather than just hoping for a fix, we invested in a solution, and that solution puts us in a solid position for the next major OS.

Update (May 29, 2020): This issue is now addressed in CCC 5.1.18, which is available for immediate download – CCC can make bootable backups of macOS 10.15.5. Choose "Check for Updates" from the Carbon Copy Cloner menu to get the latest version of CCC. Special thanks to my team members for helping put this release together so quickly, the folks at Wordcrafts for a wicked-fast turnaround on these UI translations, and for several beta testers that helped us knock out some kinks along the way.

Early last week we discovered an APFS filesystem bug in a beta of macOS 10.15.5. The technical details of the bug are laid out below, but the short version is that we're no longer able to use our own file copier to establish an initial bootable backup of a macOS Catalina System volume. To be very clear – existing backups are unaffected, and this has no effect on CCC's ability to preserve your data, nor any effect on the integrity of the filesystems on your startup disk or your backup disk. The impact of this bug is limited to the initial creation of a bootable backup.

So that's a lemon... But hey, summer has arrived here in the northern hemisphere, so let's make some lemonade!

Creating bootable backups on macOS 10.15.5

Last year at Apple's Developer Conference, Apple suggested that backup software could use Apple's "Apple Software Restore" (ASR) for cloning APFS volume groups. Initially I dismissed this – I shouldn't have to use Apple's black-box utility to do my job, I prefer to take full responsibility for my backups. Anticipating a world in which Apple continues to restrict access to APFS rather than grant it, though, we decided to invest a fair amount of time evaluating this functionality, and we've been beta testing it for the last 8 months. I don't like to lean on ASR for general backups because it has some shortcomings and doesn't give any insight into its internal activity (e.g. files copied, errors encountered), but in this very narrowly-defined case, we can leverage Apple's proprietary utility just to establish bootable backups. We posted a beta last Sunday with new UI around this functionality, and we intend to... Read More