Time Machine do you trust it

[thewall]

I’m thinking about reinstalling Mac OS I have used 700gb of 1TB i have TM running all the time, is TM fool proof or is 700gb a big ask,should I back up on another drive

 

[mw360]

It's not foolproof. I once wiped a system, installed a new OS version and then restored the back-up. I wasn't happy about the performance of the new OS so I immediately (within an hour) attempted to roll back everything using the same back-up. Except, MacOS seemed to have wiped the back-up from the disk as soon as it had finished restoring.

 

[kitKAC]

It's not foolproof. I once wiped a system, installed a new OS version and then restored the back-up. I wasn't happy about the performance of the new OS so I immediately (within an hour) attempted to roll back everything using the same back-up. Except, MacOS seemed to have wiped the back-up from the disk as soon as it had finished restoring.

Time Machine stopped including a full backup of macOS quite a few years ago (since the introduction of the SSV). You have to reinstall the macOS version you want to go back to and then migrate your data.

 

[thewall]

So are you Dayi to have to install Mac OS first then restore from TM is that how you do it I have never done anything like this