Big Sur Time Machine Migration

Howard Oakley reports a smooth experience upgrading to macOS 11.0.1 Big Sur. Good news, but I’m waiting for the 11.1 update while preparing for the Big Sur big move by getting my Time Machine updates in order: I retired the old Time Capsule, removed the hard disk and repurposed it as a local Time Machine backup disk. Goodbye NAS Time Machine backups.

As Oakley pointed out just after WWDC20, and as Ars Technica confirms in their Big Sur review, updating to Big Sur comes down to 2 Time Machine choices: 1) the legacy HFS+ hard link way and, 2) The APFS snapshot way. There is no way to migrate from HFS+ Time Machine to APFS Time Machine except by starting afresh. The default Big Sur Time Machine setting formats a new disk as APFS as shown in the video. Goodbye HFS+ Time Machine backups.

Oakley’s key advice is this:

I also strongly recommend that, whether using HFS+ or APFS to store your Time Machine backups in future, you start making a fresh backup set with Big Sur. You’ll have to do that if you switch to using APFS anyway, but following the problems which occurred with Catalina, you’ll be much better off if you archive your old backup set and start afresh.

To do that I plan to:

  1. Backup macOS Catalina 10.15.7 to 2 different Time Machine hard disks: one for archive, one for migration
  2. Turn off automatic Time Machine backups
  3. Upgrade to macOS Big Sur 11.1, then if the upgrade is successful…
  4. Wipe one of the Catalina Time Machine hard disks and let Big Sur Time Machine create a new APFS backup with auto backups.

I’ll let you know how it goes.

UPDATE
I had my backups in order and decided not to wait for 11.1 and went ahead with Time Machine APFS migration with 11.0.1. It worked out pretty well, the upgrade from macOS Catalina was smooth and trouble free, unlike the upgrade from macOS Mojave.

Time Machine migration was equally smooth. I put away my archive Time Machine backup hard disk and reformatted the 2nd Time Machine HD for APFS (4 TB Western Digital ‘Green Label’). I then let Big Sur Time Machine do a default setup which reformatted the disk again. A completely new Time Machine backup of my MacBook Pro late 2016 1 TB SSD took about 3 hours. After the backup was complete the Time Machine HD was busy indexing for the next 8 hours. I checked Activity Monitor but could not find which process was doing the indexing.

After indexing was over Time Machine APFS snapshot backups do seem faster than the old HFS+ variety. I need more time with it, especially accessing Time Machine backups, but so far so good.