I have been down many different approaches and as your file size on disk grows it boils down to some factors of approach.
- how important are my files to me?
- how much tech savvy am I willing to learn?
- what is the cost I'm willing to invest to protect my images?
My gal had lost three months of images that was taken climbing peaks in the Sierras because I was to busy (lazy) to set up a second hard drive and click a button. Hard lesson to learn when it is somebody's else's images! I vowed to never do that again!! Plus we had to the following year climb many of the Sierra peaks again.
Our files are Important to us. They show details and memories of past trip and adventures that may never be repeated. Images captured can be printed, shared, or entered into photo contest. They are a record as to where you been and could aid in behavior detail for Audubon or technical papers.
So being IMPORTANT how many copies? We have three. One is the working drives, one is the backup that is at the other end of the house and the last in in a safe deposit box. Fire flood, theft, there is always a copy off site. That one off site is only as good as when you had backed it up last.
Tech savvy. Could be as simple as cloning hard drive or letting some canned software do it for you, to writing batch commands and having the operating software run a timed back up. Further up the line is having multiple raid boxes attached by LAN through a switch.
Like said hard drives will fail from day one to whenever. Many factors that cause failures from power sags - spikes to hard drives being too full. Some have one year warranty to some up to 5 years. Search out good quality drives that have good reviews with venders such as Newegg.
I'm setting up a NAS system using three Synology 1815+ external box. They hold eight drives. Working box I have 7 - 6 TB drives configured in a raid 6 ( two drive protection) Disk volume size is 27 TB. We have close to 16 tb worth of images, yikes! The box is attached to a switch. All lines are going through the switch (LAN) and not the router to each other. At the moment a second box has 6 - 4 tb and 2 - 2 tb drives in a SHR raid and 4 tb protection. It will take three days to make a copy and will be taken off site , can you guess how long that would take going up to a cloud?. And when that is done a third copy will be generated. It gets complicated and I still need to learn more about this to make it run faster. Muscling through with a sledge hammer!
I have a shelf of smaller drives and miscellaneous boxes that I have used and since expanded to larger.
A back up is only as good as when you did it and if you have protected it.