I've had several catastrophic computer crashes. Each time, I tell myself that I am taking the steps to provide adequate backup and that it will never happen again. But it has - several times. Most recently, last week. This time it was a corrupted Windows installation.
I have an external hard drive that is set up using Microsoft's File History feature to keep a copy of every file. And I also use OneDrive. But I found that I still lost several years worth of data in the crash. But what I have learned since then is that the both automatically update the 'backup' they are creating when changes are made to files on the computer. That's fine, but this particular failure left my computer running but with the interface corrupted such that I couldn't actually do anything. I suspect that some recent files were damaged during the several hours it took for me to recognize that the computer was in trouble, and both File History and OneDrive dutifully copied the damaged files to their respective backups. So lesson learned: the only real backup is one that is totally separate from the computer and therefore not subject to corruption if files stored on the computer are damaged.
Routers are also spawn of the devil. The service we purchased from our ISP was nominally 100 mBPS, but I could never get anything higher than 30. I talked with the ISP's service tech (they are usually pretty cluefull - unlike the drones you talk to when you call their telephone service center) who was able to convince me that the problem was our old 801.11n router. So when we made the switch away from cable TV to streaming, I bought a new "gigabit' router and immediately saw a dramatic increase in speed. But the ISP also improved their service - to 500-600 mBPs, but we seem to be throttled at 100. The ISP's tech was able to measure full speed out of their modem, so the throttle is in the router. Supposedly, there is a setting that controls speed, but in my case it doesn't do anything. I've tried talking to the router manufacturer, but once they recognized that the warranty on their box had expired, the just ghosted me.
So very sorry to hear about your troubles. That sounds truly terrible. I lost some hard drives a couple years ago...I still to this day, do not know exactly what I lost. Two drives had bad spots, and while I was trying to copy data from them to another drive (an EXCRUTIATINGLY SLOW process due to the state of the two bad drives), the drive I was copying to failed. I heard some sounds, I suspect a head crash, and then the drive simply stopped powering up or anything. So, in my attempts to save some data, I ended up losing a LOT of data... This was mostly astrophotography, terrestrial photography, and then other stuff, but by far the photography (terabytes). The sheer size of the photography meant I couldn't put it on a cloud. Some of it was backed up to bluray...but, I don't even know exactly what I've lost at this point. In a general sense, pretty much all my photography from 2020 through 2024, except the stuff that I still had on my various CF and SD cards (thankfully, I had left some of my recent landscape photography on my SD cards and was able to recover!) But, I have lost so much data...and I don't even know if a day will come when I no longer go looking for something, only to find its just gone forever... :'(
Your warning is interesting. It sounds like onedrive restored to your computer bad data? That is certainly something to keep in mind. I used to have a NAS device in my home (it was really old...I think I bought it around 2011, maybe earlier, and it died some time ago.) I used to keep all my data backed up to that as well. A NAS will not geographically distribute your data like an online drive will, however as you state, if the online drive can get corrupted (!!)...the only other backup is your local one. A decent NAS is not terribly expensive these days. I had something like 8 or 12 TB on mine, and was able to run backups of my computer and have them moved to that NAS device. I generally tried to maintain good backup strategy: Keep several, not just one, as a history of your computer over some degree of time; Backup at least once a month, and if you have an "incremental" backup option then back up as often as you can with periodic "full" backups; Clone the most recent backup somewhere else as well...just in case!
In the case of my old NAS, it was a RAID system, and it had parity data so that if one of the drives failed, you could replace it and all the data that was on it could be recreated. This is a great feature for a large sized backup volume, as drives DO fail at times. I never had the issue with my NAS, and I knew it was on its last legs and had moved most of the data off (again, I lost some astrophotography on it!! Astrophotography uses a ton of data...hundreds or even thousands of frames per image, plus all the intermediate processing data, can amount to hundreds of gigs or more per image! I've been doing astrophotogrpahy since around 2011...) The device itself is what failed in this case, power supply (which I could not find a replacement for.) Still, I this thing lasted for...12, maybe 14 years?
If anyone wants a reliable backup device with LOTS of space to store a history of backups of your computer, a NAS device (Network Attached Storage, BTW) is a really great way to get reliable large volume storage space. Not just for backups even, for anything you may need or want to store on a more reliable volume than a single drive. FWIW, NAS devices still use generally platter drives. There are NVMe (SSD) NAS devices, but they are more complicated, usually a LOT more expensive, and there are sometimes concerns about becoming write-locked over time, as such devices generally need to maintain parity data which can often require additional writes just for parity, as well as some necessity of moving data around so parity data can be stored properly. An entry level NAS device can run around $150, but do your research and usually one around $400 or so will provide longer more reliable service.
Anyway, your warning is a good one! I haven't run into corrupted one drive yet, but if its happened once, it could certainly happen again. I may have to buy another NAS here, as my current computer is actually now just a cluster of SSD and NVMe drives (all my platter drives, I think, are either dead or....well, I don't really trust them anymore!) All my critical data is on OneDrive, but...I now feel I need to have a local backup as well...
for 1Password! Love it, and it synchronizes between all my connected devices.