Yes, you can try a 2-pole, 2 position switch and just switch the data lines. Power the hub from an external source so you're not switching the power lines as well. Leave the ground connected back to the computers but not the +5V.
You might need some kind of buffering, (not the data type - more to debounce the change-over), but you can certainly try it without first.
that's more like it
so is it acceptable to leave both power lines connected concurrently? I haven't looked at the pinouts yet, but I assume this from your comments
I wouldn't call it acceptable, there's a risk of destroying the USB device
or you may have the two computers fighting each other if the voltage supply isn't exactly the same.
Since you'd be having one powered port anyway, (for external 2.5"), you might as well power them all externally - plus it's so easy EDIT:
Just to expand on the underlined bit. If you switch the +5V then you're effectively disconnecting the power and reconnecting within a very
short space of time. This could induce a voltage spike into the device but I look at it this way: I wouldn't do it to my whole system, a television, or any electronic device since it has been proven in the past to kill devices.
If you leave both connected then a fault in one computer could possibly feedback into the other - why take the chance?
I prefer to leave the USB devices powered and just switch the data lines, there's less chance of a voltage spike being induced into the data lines that way also.
and how would you 'buffer' the change over? I don't anticipate that I would be switching while anything critical was running so I do expect it would be an issue, but now I'm curious
Did you mean don't
Possibly just a couple of CMOS/TTL chips wired to input/output lines, the problem being looking through specs to find what's capable of >480MHz switching. I'd need to look through my circuit library and check the web to get a better idea and see how critical it'd be.
See my edit to my previous post also.