Function on single drive?

I am still waiting, a month later, for a replacement HD to go into my Studio II edition book.  I was curious as to whether or not anyone has run one of these with only one drive to retrieve the data on the second hard drive that is still in the case?  Is the external drive capable of running while only one drive is installed?

exactly what would you like to do, to transfer the data from the defective to the replacement drive you will receive?

I’ve already done that actually, I am just curious as to whether or not the system will function with one drive installed.  I’m also curious as to whether or not the new drive, once installed, will still be in Raid 1 and copy over the data from the drive not replaced.