There are different types of RAIDs.
Sometimes the goal is to spread data over two or more drives for the sake of access speed. E.g., where if any drive fails, you lose all of your data.
Sometimes it is to provide protection against drive failure. This requires redundant data storage. You...
Until you have a Blu-Ray Video player application, you probably won't know the deal with the Blu-Ray region codes. Still, according to Disney, Blu-Ray has fewer regions than DVD. So there might be cases in which a "foreign" DVD would be outside your region, but a "foreign" Blu-Ray would not...
The record industry screwed the pooch when they made DVD-Audio and Super Audio CD delivery mechanisms for DRM. People want to be able to listen to their music in their car, or on their portable music players, even if they also have audiophile systems at home.
It's better to know that your data is toast, than to think that your data is OK when it isn't. If you know that the copy of your data on a particular DVD-R disc is toast, then you might go looking for a good copy on one of your backups, instead of just using the bad one.