I have Raspberry Pi 3 B+ hooked with two LaCie Porsche Design P'9220 1T drives set up in RAID 1. I had to increase the USB current by configuring max_usb_current=1 in /boot/config.txt and also use good USB charger and cable (really, some of the cables I had were not good enough) to get it to work reliably.
It's been working perfectly. Sure, it's not the fastest thing ever, but mostly the limiting factor is our home WiFi, not the the RasPi.
EDIT: The USB drivers I use do not need external power supply, so the whole thing needs only two cables; power supply and Ethernet. Ethernet cable is not necessary if you are ok with WiFi speeds.
I have a usb harddrive connected to an odroid c2, it used to be connected to an rpi3, but if I'm not mistaken I got 2-3x the write performance when using the odroid. I have an odroid n2 now, but I haven't bench marked it.
It's been working perfectly. Sure, it's not the fastest thing ever, but mostly the limiting factor is our home WiFi, not the the RasPi.
EDIT: The USB drivers I use do not need external power supply, so the whole thing needs only two cables; power supply and Ethernet. Ethernet cable is not necessary if you are ok with WiFi speeds.