SCSI disks in this day and age?

[freqmax]

Have a look at those SCSI <--> P-ATA bridges and those for S-ATA.

Otoh, SCSI-1, SCSI-2 is not so much in use. So it's being phased out..
But you can always build something..

[freqmax]

Of course you can use U320 drive with SCSI2 etc.. BUT the cost won't likely make it worthwhile.
But do consider that the SCSI2 SE interface is quite basic to interface with.

However with Ethernet etc.. you could put the harddrive anywhere and put the noisy harddiscs where you don't have to listen to them.

[freqmax]

Old drives = end of useful lifetime, high probability for "all you data are belong /dev/null"

[freqmax]

And the Amiga environment ain't the best place to execute a backup

[freqmax]

SCSI-1/2 <--> Ethernet would be great

Works like intended without the direct hardware dependencies.

[freqmax]

U320 is also very different from SCSI-1/2 so a serious converter will still be needed..

[freqmax]

Vintage and SCA sounds like "Vintage Quad core 5 GHz"

[freqmax]

Speaking of servers, what does electricity cost at your location?