Connect USB storage device to 2 computers at a time

I'd like to connect an USB storage device to 2 computers at the same time (With a cable, not over the network). Is this possible?

Context: I want my Raspberry Pi to save output on an external USB-storage, and then be able to read the output on a Windows XP PC.

Something like the following is the best you can hope for.

• Easily share access to USB devices between two computers
• LED lights indicate which computer has access
• Gain instant access to your USB devices by plugging one USB cable into your computer
• Simply press a button to switch individual USB devices from one computer to another
• Both computers have direct access to the printer thanks to Automatic Printer Sharing
• Plug and play set up and easy to use with no network required

Since we don't really do product suggestions here at Superuser here is a single Example of the device described. There are others that'll work similarly to this single example. You will be unable to share a USB device with multiple computers at the same time.

Like the Serial devices that came before Universal Serial Bus devices. USB devices are not designed to be accessed by multiple hosts at the sametime. Its the same reason you cannot share a USB device with a VMWare Guest Operating System and the Host System at the sametime and have to disconnect/connect the device.

Software people won't like it but from a hardware perspective there is no reason two systems cannot have access to the same storage. If one only writes and one only reads there is no issue except trying to read from a file not yet complete. I am sure that can be resolved by simply waiting a prescribed amount of time before trying to read the file. If both systems want to read and write a simple semaphore can be created using files.

This would be a safe way to transfer data between systems. Unless the systems execute the files viruses on one system could not infect the other system. The infected file would be present but it would just be a file.

I have considered designing such a device myself but never seem to have the time. A development board with two USB slave ports (B) and one USB host port (A) could do it. Just pass all commands arriving on either slave port to the host port. Plug a USB drive or thumb drive into the host port. It wouldn't be quite that simple but that would be a starting point.