Have you come across hardware failure on your server ? Did it affect you bad ?
What are the ways to make sure that it is not going to hurt us bad ?
Depends on the hardware failure. It's all about contingency, backups (which have to be regularly tested), business continuity, disaster recovery, and your ability to recover as quickly as possible with a previously tested model.
I think if you are with a good data centre, there is a good chance that you are safe. The main critical component that can fail is the storage device. HDD or SSD. Both shows signs of it much before it fails. There are ways to monitor it and take precautions.