I've been running my present setup for a few years with no issues, mainly because I still edit in SD (most HD files tend to stutter on playback.) My footage files are running on 3 internal 1-TB drives which are NOT in a RAID configuration. I just picked up 3 3-TB drives to upgrade/replace those drives am considering RAIDing them together for better playback performance and data loss prevention. So I'm looking for advice from anyone presently using this setup or knows enough about it to point me in the right direction.
I'd set it up as striped raid set (raid 0). Mirroring provides a level of recoverability from a drive failure but it's slower. If you want the performance, just use the striped raid option.
Use quality drives rather than inexpensive or refurbed drives. Check reviews. Check the drive integrity regularly. Head off a drive failure headache. I like DiskToolsPro for regular maintenance. ProSoft Engineering's Data Rescue 3 is the best recovery tool I've tried.
I had two new western digital drives fail within a year. WD replaced the drives.
Get a back up drive for your raid & system drive so you can recover from an unexpected failure.