USB/Firewire HDD. Using both ports at the same time

Is it possible? I mean two different computers accesing the HDD, one using the USB port and the other one the Firewire.

If it's not, is there any portable HDD u can access with 2 PC at the same time (Networking HDD aside).

Ty

generally, no. There are some commercial units that allow multiple systems
to co-access a single drive, but you can afford the power,cooling, and systems
cost. The USB & FW ports on an external HD are for setup convenience and are
use EITHER/OR, not concurrently.

There is a single IDE controller chip in your USB/FW enclosure and the chip changes its operating mode depending on what interface is connected. You can not have both at the same time.

And even if you had simultaneous access to the hard drive, a myriad of sharing problems will occur. You'd need a special multiuser filesystem.. And Windows doesn't support such things of course