Confirmed: Big Sur Time Machine backups are NOT bootable

[zorinlynx]

One thing I've liked about Time Machine up until now is that a Time Machine backup is bootable and will restore the system to the exact version of MacOS it was running at backup time with all your data.

This is no longer the case with Big Sur. I made a new backup of a test machine and it only contains the "Data" partition, and is not bootable. I just wanted to make everyone aware of this since it could end up being a big problem if you assume it still works the same way as before.

 

[EmmEff]

I didn’t even know this was possible. In the past, I have booted into recovery mode and restored from Time Machine backup.

 

[decypher44]

One thing I've liked about Time Machine up until now is that a Time Machine backup is bootable and will restore the system to the exact version of MacOS it was running at backup time with all your data.

This is no longer the case with Big Sur. I made a new backup of a test machine and it only contains the "Data" partition, and is not bootable. I just wanted to make everyone aware of this since it could end up being a big problem if you assume it still works the same way as before.

So, what would we do? Internet Recovery, then restore everything else with Time Machine?

I’m not understanding why Time Machine wouldn’t copy everything, then restore everything. To be fair, this is the first new Mac computer I’ve owned in 7 years, and I didn’t use TM until now. Maybe I’m not understanding it exactly.

 

[halofan56]

You know they made a change and added SSV? Its a signed signature volume. That's why CCC and I think, Super Duper is having issues. I am assuming Apple is aware of this, since they have a issue on their hands. Like Emmett says, I never knew it was bootable. I use osMAC Journaled format for data only.

 

[halofan56]

So, what would we do? Internet Recovery, then restore everything else with Time Machine?

I’m not understanding why Time Machine wouldn’t copy everything, then restore everything. To be fair, this is the first new Mac computer I’ve owned in 7 years, and I didn’t use TM until now. Maybe I’m not understanding it exactly.

I don't think it was ever bootable. It was only designed for restoring files and apps, also using for Migration Assistant for transferring your data in case of a re-install. That's why you have Carbon Copy Cloner software and Super Duper. CCC is planning to release hopefully this week to address Big Sur. Super Duper is going to take a while.

 

[ondioline]

I actually prefer it this way since Catalina, with the segregated OS volume and data volume. Restoring, in the past, always gave me the feeling I was dumping a bunch of crap I didn't necessarily want back into a fresh system. Thats why I always reinstalled and manually copied the stuff over from TM.

Now when you restore from a snapshot you know the OS volume will be for sure unblemished from a garbage avalanche of random adobe scripts

 

[halofan56]

I actually prefer it this way since Catalina, with the segregated OS volume and data volume. Restoring, in the past, always gave me the feeling I was dumping a bunch of crap I didn't necessarily want back into a fresh system. Thats why I always reinstalled and manually copied the stuff over from TM.

Now when you restore from a snapshot you know the OS volume will be for sure unblemished from a garbage avalanche of random adobe scripts

Under Big Sur, my time machine works great!! I am waiting for Carbon Copy Cloner update software this week, to finish making my other external drive bootable. I emailed them yesterday, they said the beta is running smoothly, anticipating update release this week.