Boring (but important) stuff
Not exactly the most interesting of topics but included here to reassure you.
As a professional wedding photographer, I am fully insured. Some venues will not allow photographers who do not have adequate levels of insurance.
I have backup cameras, lenses and lighting equipment with me at all times. Should something go wrong with a piece of equipment, whilst I might be crying on the inside, coverage of your day will not be impacted – I will simply get my backup kit from my bag and continue capturing your day.
My cameras allow for the simultaneous recording of all images to two separate memory cards. If one memory card fails or corrupts, your images are safe on the other card.
As soon as I get home, every image is downloaded from my memory cards to my computer and the computer is backed up to the cloud. I take additional backups to a raid array and a portable hard drive (which is stored away from my home).
Although I would recommend you have at least two copies of your images on separate laptops or computers, I retain your images for a period of three years. In the event that you lose both sets of your images, I can make the images available for you at no extra cost.