The argument has already been touched recently in other threads. In few words, when the matter is saving the data of one 1 disk the best solution is adopt a backup strategy for that purpose. You can have a backup strategy that involve one or more spare disks. If you are on sticks copy machine by three slots are also a solution.
Involving 1 more disk in raid 1 is never a good solution for different reasons the most important one: against a disk failure you put at risk the full raid set; then softraid is never running properly and never good for your disk life beside slowing down your system. The advise is a good backup strategy also against the possibility to adopt other kind of raid involving more disks, increasing your own expense at the important cost of losing a direct touch on your data.
