I’m a long-time TidBITS reader, from the late 90s or so. I started reading just before switching to use Debian Linux(!) but have kept reading since Adam’s commentary is always interesting, and most of my family use Macs. It’s my first time posting here, hence the prologue.
I tried to use a 2014 Mac Mini upgraded with an nvme drive to run as a family Time Machine server but suffered issues with either AFP or APFS (Apple File System) volumes causing corruption.
Wary of corruption and the fact that the 2014 Mac was mothballed at macOS 12 I installed Debian on it and reformatted the generous nvme drive as a btrfs volume. It was very easy to get this running samba (the open source SMB/CIFS file server) with Time Machine support.
The Time Machine backups have been running for over 4 months without a hitch. In addition to that, btrfs (apart from bitrot protection) gives snapshot support. Although it might seem incongrouus to take snapshots of an APFS volume which itself has Time Machine snapshots within it, it allows roll-back to an earlier version of a Time Machine volume if needed. (I’m wary of corruption re-occurring). And while the btrfs snapshots may not be sharing data between them as efficiently as APFS volumes themselves, these still perform pretty well. For example, these weekly snapshots, on a system with a lot of churn, show the following:
btrfs fi du -s *
Total Exclusive Set shared Filename
...
351.41GiB 394.34MiB 350.97GiB 20250510-timemachine
362.40GiB 241.36MiB 362.10GiB 20250517-timemachine
372.74GiB 299.67MiB 372.37GiB 20250524-timemachine
The exclusive data shown for each snapshot is typically well under 400MB.
Enthused by this low-cost solution, I’m trying an even lower-cost approach for a “travelling server”. This is a Mele Quieter 4C box with a 2TB nvme disk, about the size of a large, boxy phone. This gadget has an Intel 4 core N100 CPU, 8GB RAM and 128GB eMMC onboard storage, is pretty robust and well-made, and are apparently often used in industrial settings. In the UK the total cost of the box and drive was about £250.
I make sure that there are always three copies of our data, so I don’t mind having just a single nvme drive in a backup device. The benefit is you can grab that nvme stick and put it into just about any reasonably modern Linux machine or USB stick reader and simply mount it.
Sorry for the long explanation, but since Adam asked for alternatives, I thought I’d mention this approach.
p.s. I don’t do this but it should be a snap to serve printer sharing from any Debian box using CUPS.