Is there a way to link two hard drives together with a hub or something?
There are USB external RAID subsystems that may do this. Possibly easy to do from scratch, somewhat doubtful about inserting an existing Tablo drive into one for the purpose of a logical concatenation.
What about a USB hub? Would the Tablo recognize two HD drives plugged into a USB hub that is plugged into the Tablo?
No, that would still appear as two separate drives.
The one device I can think of that might fit the bill is the Drobo - and I have no personal experience of one. I just kind of know what it does since I had an acquaintance that worked somewhere in the Drobo organization.
I wounder if Table would be able to recognize two drives via a USB hub?
No, it won’t. The Tablo can only use one drive at a time. Using a USB hub just lets you connect more drives, but the Tablo won’t use them.
There are USB drive enclosures available that will make multiple drives look like one bigger drive (as cjcox said), but they’re not cheap and you’d loose all your current recordings setting it up. So you’re better off just buying one bigger drive and using it.
Like mentioned earlier. You need a device that can do raid. That can make both drives appear as one. Unfortunately that means formatting the drives when first added to the array.