I select a single drive and the "analyze" button is enabled. I select all drives, the "analyze" button grays out.
I think it a good idea to allow a person to analyze all of the drives, it's quite logical that I will want to do that. Instead, I select drive1, analyze, wait. Select drive2....all the way up to drive8 in my case. It can take more time than I want it to, just to see if my drives need work or not.
So I think it a good idea to allow multiple drives to be selected and analyzed, maybe even put a "analyze all" button on.