The explicitly mentioned mdadm so they are not using the "raid" on the cards (anyway, at that price it almost always is software raid implemented in the driver).
With the linux md software raid you can kick off background scans. Read the md(4) man page and linux/Documentation/md.txt for the gory details. There is a lot of good stuff in there.
I love Linux software raid. It has been fast and robust.
"The most important thing in a man is not what he knows, but what he is." -- Narciso Yepes