"Rare hardware malfunction" brings down Digital River, Directtrack networks
startribune.com
startribune.com
As for redundancy, yes, that's a good idea, but there is a lot that can go wrong even if you've planned for redundancy. Have you ever yanked a disk out of your RAID setup during peak load? Why not, don't trust the redundancy? And that's why things break, even if the architecture is designed not to.
Its pretty surprising that Microsoft (who run a reasonably functional store on xbox) cant figure out how to run their own online store.