Frequently asked questions about CCC and macOS 11

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With the announcement of macOS Big Sur, Apple has retired Mac OS X (10) and replaced it with macOS 11. As the numeric change would suggest, this is the biggest change to macOS since Apple introduced Mac OS X roughly 20 years ago. Following a progression that we've seen in the last several years, macOS 11 is more like iOS than ever before. The system now resides on a cryptographically sealed "Signed System Volume". That seal can only be applied by Apple; ordinary copies of the System volume are non-bootable without Apple's seal. To create a functional copy of the macOS 11 System volume, we now have to either use Apple-proprietary tools to copy the system, or install macOS onto a backup.

Can CCC copy the macOS System volume?

CCC will be able to use Apple's APFS volume replication utility ("ASR") to copy the System volume (we field-tested that functionality for the flawed 10.15.5 update). As of the latest Big Sur Beta, however, Apple's APFS replication utility is not working correctly with the Signed System Volume. As a result, ASR-created copies of the System volume are not bootable. We regret that Apple was not able to resolve that before shipping Big Sur, but we are working with Apple to resolve these issues.

Can I still make bootable backups on macOS 11?

Yes, absolutely. There are two distinct approaches to making your backups bootable on Apple's new OS. When Apple works out the problems in its APFS replication utility, CCC will leverage that directly to copy the System volume and produce bootable backups. In the interim, you can install macOS Big Sur onto your APFS-formatted CCC backup volume if you would like to make it bootable.

Does CCC back up all of my data, applications, and system settings?

Yes, absolutely. This part of CCC has not changed — CCC continues to provide complete backups of all of your data, applications, and system settings. Additionally, CCC offers support for snapshots, giving you access to older versions of your files.

Does my CCC backup have to be bootable for me to restore data from it?

No. Bootability is a convenience that allows you to continue working if your startup disk fails, but it is not required for restoring data from a CCC backup. You can restore individual folders and older versions of files (i.e. from snapshots) using CCC while booted from your production startup disk. CCC backups are also compatible with Migration Assistant, so you can use Migration Assistant to restore all of your data to a clean installation of macOS (e.g. on a replacement disk).

Should I upgrade my Mac to macOS Big Sur?

Major system upgrades are often disruptive, so we have always recommended a very conservative approach to applying them. Consider the following:

  • Is the upgrade required for my Mac?
  • Will this upgrade improve the performance of my Mac, or degrade performance?
  • Does the upgrade provide some functionality that will make me more productive, or otherwise greatly increase my enjoyment of using my Mac?
  • Does the upgrade fix a problem that is preventing me from effectively using my Mac?
  • What software will no longer work after applying the upgrade?

If the upgrade turns out poorly and you have to downgrade, you certainly may downgrade using a CCC backup from an earlier OS. These sorts of procedures require time and effort, though, so you should weigh that potential hassle against the potential gain of the OS upgrade.

Lastly, we recommend that any users that rely heavily upon the availability of their Mac for work or other productivity consider waiting for several OS updates before making the upgrade. The early releases are exciting, but that excitement involves risk. Early adopters will find some shortcomings and bugs which will be resolved in minor OS updates.

How do I upgrade my Catalina (or older) backup to Big Sur?

After you upgrade your Mac to Big Sur, and only after you have decided to commit to the Big Sur OS, resume the backup of your startup disk to your CCC backup volume. If you would like the backup volume to be bootable, install macOS Big Sur onto the destination.

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