Time Machine Automatically formatted my drive APFS w/ Case sensitive?

[Makisupa Policeman]

I set up Time Machine on Monterey 12.2.1 on a new 14” MBP backing up to an external HDD and it auto formatted to case sensitive APFS? Why would it do this? Won’t this affect things like file naming and permissions when trying to restore from the backup?

 

[chabig]

That's just the way it works. No need to worry. Restore will work fine if you need it.

 

[Makisupa Policeman]

Thanks. I should probably use the search function more often as this was discussed elsewhere. I appreciate your reply

 

[bw44]

My regular external USB hard drive (screenshots Disk 1) is formatted Extended (Journaled)

I erased and reformatted a second (older) USB hard drive (screenshot Disk2)
as Extended (Journaled) and backed up with Time Machine. The backup appears to have worked, but Mac OS (Monterey 12.6.3) reformatted it to APFS.

Disk 1 (WD My Passport) was originally formatted on an earlier version of MacOS. I tried erasing and reformatting Disk 2 (Seagate) on both 12.6.3 and an older iMac running High Sierra, but my MBP still reformatted during the first backup as APFS.

My question is: Why does the data appear to be stored very differently on the two disks (see screenshots) and can I use either disk to recover my system?

Thanks for any advice or clarification.

 

[Brian33]

Why does the data appear to be stored very differently on the two disks (see screenshots)

Time Machine to an HFS+ volume uses the "hard links to directories" feature of that filesystem. Time Machine to an APFS volume uses the "snapshot" feature of the newer APFS filesystem. So the structure differs depending upon the format of the backup disk.

can I use either disk to recover my system?

Yes.


APFS is preferred by TM. When you start a new backup series with a recent macOS version, it will always format the target disk as APFS (case sensitive) -- even if you've formatted it HFS+ first. If you re-use an older TM disk that already has a backup on it and tell TM to continue to use it, then TM will allow it to stay in HFS+ format.

 

[bw44]

Time Machine to an HFS+ volume uses the "hard links to directories" feature of that filesystem. Time Machine to an APFS volume uses the "snapshot" feature of the newer APFS filesystem. So the structure differs depending upon the format of the backup disk.


Yes.


APFS is preferred by TM. When you start a new backup series with a recent macOS version, it will always format the target disk as APFS (case sensitive) -- even if you've formatted it HFS+ first. If you re-use an older TM disk that already has a backup on it and tell TM to continue to use it, then TM will allow it to stay in HFS+ format.

Thanks very much — you answered both my questions! I must have used the HFS-formatted disk on an earlier MacOS and told it to continue using that format. Didn’t remember.