Build Your Own $2.8M Petabyte Disk Array For $117k
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.
Ahead of IPO, Vonage Faces User Complaints
You can get them to change the codec you use to a less bit-hungry one. That has helped a few people I know who have Vonage.
You can test your connection to see how it will behave http://testyourvoip.com/ and you can try different codecs to see what the difference is. Try it a few times throughout the day to try to characterize your line better.