So my initial idea was to keep all (!) my files in three external hard drives: One for essentials (1TB), and the other two - the exact copies of all the files (3TB each). By all files I mean including my first drawings with CorelDraw when I was maybe 5. So I have bought ADATA HM900 3TB (formatted as FAT32) portable hard drive (the one that needs the external power source), and copied all my data from different computers there (about 800GB), both Windows and linux (I've been using Windows for over a decade and now I'm on linux). I have done the same with another hdd - Maxtor M3 Portable 1TB (1TB will suffice for now), formatted as NTFS. I did not care about filesystem differences (including ext4 on my linux machine), and it all worked well for some half a year. However, although having used those hdds properly (no physical shaking, no holding upside down, safe removal, etc.):
[1] I started getting input/output errors on my 3TB drive when copying files, mostly, but not only(!) files containting .git foder. After that, copying process was terminated, and I could not reach the folder that contained the "bad files". Even after disk restore (the default Windows one, right click on disk properties) I did not manage to recover all the files. Btw, that was certainly not the reason of files over 4GB, since I have none of those.
[2] I started getting input/output errors on my 1TB Maxtor hdd (NTFS) with the same problem, with different folders and files though (there were no .git folders in this case)
[3] On copying files from linux PC to Maxtor hdd today I got a crash (the pc just froze, I restarted it), after which neither linux nor Windows PCs detect this hdd after plugging it in
[4] I have bought another hdd: ADATA HC500 1TB, and formatted it with ext4. However, windows PCs could not recognize this hdd (it appared on Control Panel->Disk management though). So, after having lost some files and some temper, I am wondering how could this situation could be improved. Basically, the problem statement is this:
How could I use at least two HDDs (and which filesystems should I format them to) for identical copies of all my files with the ability to plug them in both linux and Windows PCs (I still use Windows sometimes), and minimizing the risk of such occurences happening again. I have a Google Drive folder with all the necessary screenshots: gDrive_link