I have a WD 120 ata 100 mounted in an ADS DLX 185 housing. It's running off of USB 2.0. I am getting ready to bring another similar unit on line and I need to shut down the current unit. I am going to try to run them both off of one fire wire outlet.

Now: the ADS book says to demount the running drive by clicking on "Safely Remove Hardware" icon then selecting the drive letter to demount. When I do that I get the following message

Problem Ejecting USB Mass Storage Device
"The device 'Generic Volume' cannot be stopped right now. Try stopping the device later"

Once before I went into device manager and diabled the drive. Is this safe? Also I noticed that there is an option within the drive's system properties to "optimize for quick removal" which disables write caching and allows safe removal with out using Safe Removal icon. Any real downside to stopping caching on a back up only drive?

The 'stop caching' shouldn't hurt a thing. Also, I've used many USB devices and never have used the "Safely eject hardware" screen. I just plug them in and unplug them. Unplugging usually brings up the above screen with the "Show icon...." box checked which I uncheck then close the window. As long as the device isn't in (active) use at the time of the unplugging, there shouldn't be any problem.