Is it safe to keep 2 minis connected by ethernet cable permanently?

Ian R. Brown wrote:

Is this likely to cause any problems?

Hi Ian,

Aren't they already on the same network at your home? If they are already on the same network there should be no need to connect them via ethernet cable.

If they are not connected to your network, connecting them to each other via a permanent ethernet cable should present no problems.

See Use Ethernet to connect two Mac computers - Apple Support

I would recommend using AirDrop. If you are not aware of AirDrop or how to set it up and use it, please click on Use AirDrop to send items to nearby Apple devices - Apple Support to learn about it and how much easier that is than using files transfer protocols.

I meant ... are the 2 minis already connected to your home network, either via WiFi or via wired ethernet? If that's the case, it would not be necessary to connect them directly to each other with an ethernet cable.

AirDrop uses WiFI + Bluetooth. I really like it. But it depends on how frequently you want to transfer files and how large they are. The Bluetooth part establishes the connection, the WiFi part does the file transfer. AirDrop "can" be as fast as wired ethernet because the devices are close to one another ... but because it's still WiFi it's subject to factors in the WiFi environment.

What are you trying to accomplish?

I would never try to transfer that much via AirDrop. I think it's fine for occasional transfer of a handful of files or images but ... 30GB? Nope.

Are the two minis just standalone machines, not on your network?