Time Machine for local + LAN backup

I have 2 Mac Minis – an M1 running Ventura (13.3.1), and an Intel i5 running Monterey (12.6.5). The M1 Mini has a 6 GB external drive with a 4.5 GB partition for archive and media and a 1.5 GB partition for Time Machine. I would like to use the Time Machine partition to back up both Macs. I am have not been able to find clear step-by-step instructions that actually work for my situation.

All of my search results seem to be for older operating systems. Also, many results focus on backing up several remote Macs. I need a solution for one local and one remote.

I can’t even find current information about the preferred disk format. Most articles insist that HFS+ is best for spinning disks and APFS is only good for SSDs… Is that still true?

I’d very much appreciate any wisdom from the group.

I have an old Mac mini running Monterey with an external drive that is a wireless Time Machine target for my M1 MacBook Air. I set this up when my Time Capsule became untrustworthy.

But I have not been able to use that external drive as a Time Machine target for the Mac mini itself, and I’m not sure why.

“The most compelling argument for retaining HFS+ is on rotating hard disks, because APFS can result in severe fragmentation, most importantly in the file system metadata, so causing degraded performance; as SSDs don’t suffer those performance penalties,”

Should you continue using HFS+? – The Eclectic Light Company

I’m not certain if this works on a single drive or not:

Partition the 1.5 and then use one partition for local TM, and the other for remote?

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Question, what is being backed up to the 1.5 gb partition? And how do you backup the 4.5 GB partition? l’m having problems understanding all the pieces.

I think you would have to share a partition so that it is visible over the network. I’m not sure whether you could simply share the existing 1.5 GB partition and then connect to it from the remote machine (a Time Capsule can do this), or, as @Vincent_Ardern has suggested, create another partition for the remote machine.

I’ve seen this argument before, but never in a recent article. So now we have some confirmation that this is still relevant.

Unfortunately, it is moot for me because I want to encrypt the partition. Apparently something changed since I set up my last external disk, because encrypting a volume in the Finder in Monterey automatically makes it APFS – even if it was originally HFS+.

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That would work, but I’m trying to limit the number of partitions as much as possible to keep things flexible.

In theory, the 1.5 GB partition is for TM backups of the internal SSDs of 2 Mac Minis. The 4.5 GB partition is for archive and media and does not have a TM backup.

Don’t worry, the 4.5 GB partition has a SuperDuper clone backup to another spinning drive, as well as cloud backup to BackBlaze.

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I’ve shared time machine drive for backup from another computer. Here’s an apple support article

That seems to be working! My old Mac mini is happily backing up to a new APFS volume that I just created on the local external drive, which was already being shared for a wireless Time Machine backup of my MacBook Air).

My mental model of disk partitioning just got a good kick in the pants! APFS adds a whole new level of flexibility.

(And, in case anyone cares, I run APFS on my backup disk drives, all of which are old-fashioned G-Drive brand spinning drives.)

Just to be clear, because nobody seems to have talked about this yet.

I’m assuming these figures are actually terabytes (TB), not gigabytes (GB)?

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Good catch :grinning:

There was a time when I would have been impressed by a 1.5 GB drive. The first PC I used only had a 10 MB.

Whoops! You’re absolutely correct. 6 TB drive. Terabyte. Not gigabyte.

Thanks for all the suggestions. I figured out a solution that works for me and might help others as well:

It seems that local TM backups can only be done to a dedicated volume. Remote TM backups can be done to a shared folder. The remote TM backup is to a shared folder on the 4.5 TB partition. this folder is excluded from my BackBlaze backup. The 1.5 partition is only used for the local TM backup.

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