The chances of them failing are pretty slim. However, now that you have talked about them failing Murphy's law states that they will now fail in the next few days.
They will fail at some point in time, and should be doing regular backups. Backing up your files using an online service is also another possibility. (Or RAID/WHS/home linux server)

They will fail at some point in time, and should be doing regular backups. Backing up your files using an online service is also another possibility. (Or RAID/WHS/home linux server)