I always backup my data on multiple online and physical drives as even a backup can go bad. It is always a good plan to make sure those sources are healthy and move the data around regularly as storage media can degrade and corrupt over time. Don't just back up all your data and photos to an external drive and stick it in a closet as it will corrupt with time or could be subject to a physical damage like electrical, flood, theft, or fire so consider offsite storage as well. I read yesterday that our grandkids may not have the digital photos of ours when they get older due to drive and media failures losing the images and that is scary to even think about.
Today my primary physical drive decided to die and now I am spending my time finding backup data and transferring data. This is a tough day for this to occur as I just received my new DJI Inspire 1 UAV with a 4k camera and really want to go test fly it, but the drive data and work take priority.
So check your backups often and backup your backups. Always plan and prepare for a failure and your data will be safe.