Old MacMini with external drive as a network backup machine?

[Giuanniello]

I got a 2015 Mini which sees little to no use, back in time swapped HD with an SSD (and broke the led and remote connector in the process :-( ) thinking I might attach an external HD and use it as a backup machine for the other devices on my network, is it doable?

 

[opeter]

Yes it is. Just share the HDD within macOS. Also disable sleep on that machine, if you want constant availability trough network.

Nastavitev deljenja datotek v Macu

Delite datoteke in mape v Macu z drugimi osebami v vašem omrežju. Delite celoten računalnik Mac ali določenim uporabnikom dovolite dostop do določenih map.

support.apple.com

Or this (should still work in newer macOS):

 

[thisispeak]

…depending on how/what you want to backup, Carbon Copy Cloner might be worth a look (by comparison to TimeMachine).

I use that to back-up a machine running OS X Server to a network volume, it's set to run on a schedule overnight, writing to a disk image. It auto connects, backs-up, then disconnects.

If you've got Wake for network access (or similar enabled) you can also play with the power saving a little, so things aren't spinning 24/7.