Fastest “normal” way would be write it to a USB 3 drive on machine 1, read from drive later on machine 2. An SSD would be best. Even with having to do the write and read in two phases, I’d still expect it to be faster than a 1G network.

(Less normal ways would be things like Thundrerbolt SSDs, 10G or 40G ethernet for direct transfer, etc. But if you have that kind of tech already in place, then you’re not asking. ;)

Mine is sadly over an order of magnitude higher than this…

It’s not Thunderbolt - it’s just a USB disk enclosure with the cheapest possible 2.5" hard drive - yes, a spinning rust hard drive. The only thing you get over something $100 less is it stacks nicely with the Mini.

I’d say hard pass. What might work better is an external powered enclosure for the M.2’s, as that would reduce the power budget your Mini is trying to satisfy.

That’s essentially what I do. Bunch of drives, each formatted individually, then pooled with MergerFS. Get a new drive, add to the pool. If a drive fails, it only loses that much of my backup; rest of the disks are unaffected. All the advantages of storage pooling without the redundancy (which here is useful).

Best you’re probably going to be looking at is a Tesla card of some variant, and in a 1U without external power support it’s not going to be beefy. You’re not getting anywhere close to an RTX anything in that server.