I tried to transfer some data off my mother's hard drive with several hundred gigabytes of photos and videos, which spanned most of her life.

I decided to format the hard drive I was copying the data to.

I formatted the wrong drive.

Well, you didn't shred it so there's still hope.

Well you shouldn't keep everything on a hard drive in the first place.
With digital formats replacing everything it is very important to properly back up stuff. Which is why tonight I should make an online backup if my NAS

@AndSoWeCode well, to be nitpicky, "online" is just another companys harddrive...

@gathurian "online" means somewhere that's plugged in and available on-demand. Your own hard drive is "online". Offline means something that sits usually stacked in a shelf or in a box somewhere and not plugged in.

Per the usual saying: RAID is not a backup. Just because you're more or less safe from the extremely rare hardware failures, you'll be easily a victim of either ransomware, or an accidental format/delete or something. Same for stuff in the cloud.

An offline backup ensures that even if you're stupid enough to lose everything (you have to assume that you are, since otherwise you'll get burned by a surprise), you still have a copy stashed somewhere, safe from modification. Today I was actually stupid enough to lose data just like that, but reacted in time and managed to evade a disaster.

That's why, even if I have stuff on my machine, my wife's laptop, and a NAS with RAID 5 configuration, I still rely on an offline backup to an external HDD (SATA over USB3 - it's cheap).

Testdisk can recover the partitions or atleast recover the info. https://cgsecurity.org/wiki/...
Good luck.

Yeah I got all the data back, but it was all out of order and messy... She wasn't impressed to say the least :(