Question VPS with Plesk: Options to keep server live in case of server failure

[Ihtshama]

Hello, I have hosted few websites on one VPS. But i am always worried about server failure if it happens. What options one may have in this case? How i can make sure that in case of failure, my clients website can be kept live from another server or source? Please share your thoughts. I am sorry if i couldnt put it in the right way, as i dont know much about RAID storage etc.,