Raid 1

you will have a problem

i know i will have a problem is there any way the data wouldn't be lost

Do you have a backup? If not try Drive Savers or something if youv'e got the $$$

your question is raise another question.
If course when the a drive fails the mirror fails. Now of your asking if one drive fails how are you going to recover from that problem.
Here is what your do, replace the drive that fails, make sure your replaceing it with the same size ok. Then use your raid software to sync the files again.