In my home I have three systems using WD Raptors as primary drives and a RAID 1 set as secondary. The primary drives hold the OS and software. The RAID set is for data storage and these are much larger drives. I make frequent backups of the entire primary drive and these reside on the secondary. This allows some disaster recovery or an alternative to system restore. It's not a perfect system. The primary drive needs to be the working drive and be the fastest. The secondary (storage) is less critical as far as performance but needs to be more secure. This is why I chose RAID 1. It won't protect against everything but it will improve the chances for data recovery in the event of hardware failure. Hope that helps.