I have three USB disks I want to arrange into a concatenated disk set. One is Western Digital 2TB and is 'always on'. The other two are LaCie and have on-off switches 1 TB each. When I power the two drives up (one at a time), the first one fails 50 percent of the time, regardless of which one is first. I can power it off again, power it on again and it's fine. They worked great (as single drives) until I tried this so I figure I'm doing something wrong. Thoughts?