I'd like to add two or three hard drives to a common SBC like the Raspberry Pi or the BeagleBone Black. I'm not familiar with hardware or the terminology, so my searching has been unproductive so far.

What kind of hardware expansion options are available and where are they to be found onine?

Single board computers with multiple sata ports are rare, I think.

Example 4 sata http://www.commell.com.tw/Product/SBC/ME-C79.HTM

USB. Externally powered.

I have a couple of "button USB drives" on my pi3, but for real capacity, you are needing a powered USB hub.

Some SBCs have SATA port(s). The freescale i.MX6 platform got pretty popular because it had one. The cubox ones too, although power delivery is a slippery slope. So powered hubs and docking stations with their own power to play it safe-ish. Lots of wires and a power strip for what would otherwise be a single "appliance".

I have two toshiba usb drives, they definitely need a powered hub. Enough so that I can't even use both of them on the same powered hub. I also have an IDE (PATA since 2006-ish) docking station of sorts, the guts of an enclosure anyway. And a blacX by thermaltake SATA docking station. Only good for 2TB or less drives and meant for full sized spinning rust, not those tiny SSDs. All of which work well in a favorable wind.

I am hoping that there is some kind of "shield" / "hat" / "cape" available on the market already. I'm looking just looking to host two or three drives, not run a data center.

Later there might be something like GnuBee Personal Cloud 1 open-source NAS. But that is just vaporware at the moment.

Power is the big issue - at least on the pi's. And the shared wifi-USB bus.
You can stack cards, but you still need power. Welcome to the real world.

Power is the easily solved issue in this question.

You think ?. Good luck then.

Yes. As far as I know, power the cards from their own supply and feed the SBC from the cards.

Any tips on cards that can be used to add drives?

This WD PiDrive Node Zero is getting close:
http://wdlabs.wd.com/products/pidrive-node-zero/

It looks like it is only for a single drive, however.

As expected, the periperal has its own power and is used to feed power to the Pi Zero.

You can get SATA port multipliers.

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I wouldnt bother with a SBC for multipule SATA HDD/SSD use. USB 2.0 is too slow, you'd need an external USB hub, external HDD caddies, power adapters, mess. Gah, sod that.

Even with a SBC with a SATA port and multipliers will have bandwidth issues in some (many?) situations. (and I'm not aware of any of the SBCs with more than 1 SATA port)

But if you really want to, comparison of single board computers-

https://en.wikipedia.org/wiki/Compar...oard_computers

Go to the ' I/O interfaces and ports' and find something with a SATA 2 or SATA 3 port.

There isnt an exact definition of a single board computer...but IMO a normal Intel Mirco ATX board with a non-standard soldered in CPU doesn't count.

Might as well just get a normal mirco ATX board with a socket. Not really any more expensive, you'd get newer less power hungry CPU and its upgradable.