When working with redundant disk drives in a RAID array, it is very important to frequently backup the data. We just assessed a setup where the data stored on one drive is mirrored to the other in real time (RAID 1). In this particular case, the second drive failed shortly after the first without any of the data being backed up before the first drive crashed or during the 2-week window after the first hard drive crash and the second hard drive crash. Sadly, we have to report to the client that this project is unrecoverable.
If you were told that your data is protected because it is on a RAID, whether it be a corporate server or a home NAS, you may want to talk to your computer service technician about setting up a solid backup solution to help avoid unnecessary data loss in the future.