It seems that NONE of the external USB devices that are on my desk (64 GB EMTEC, 64 GB and 4 GB ScanDisk, 1 TB HDD in Lacie enclosure) are supported when connected to the laptop. Only internal laptop hard drive is listed as a usable device! I cannot use this drive for experiments, I need its installed operating systems for other tasks of my work. Surely nobody in the sane mind would use USB sticks for RAID data storage but how am I supposed to evaluate your product without buying the dedicated server first? Also, all external USB devices I have tested work absolutely fine under Linux.
Try to reboot your system, and be sure you alreay plugged in the USB or HDD that you would like to use in your laptop, beside I assume you are using a softwar RIAD in your settings right?