I sometimes use Dropbox, iCloud or OneDrive.
I find it is when you save and then save again very quickly that can cause problems.
Archicad handles it fine, the cloud drives don't seem to keep up.
Yes, the BPN is simply the last PLN that you saved - one save back if you like.
When you save, the existing BPN gets deleted (if there is one), the current PLN file alrady existing gets renamed to BPN and then the current on screen file is saved as the latest PLN.
The auto save is a bit different.
These only exist while you have a file open.
Close it in Archicad (with or without saving first) and the auto save file will be automatically deleted.
Only if Archicad (or your computer) crashes or you force quit Archicad, then the auto save file is not deleted and you will be prompted to recover it the next time you start Archicad.
So if you turn the backup files off, you will have no backup files at all, but you should be save if your system/program crashes.
Personally I like the extra safety of the BPN.
I have had corrupted PLNs in the past (no way to open them) and occasionally I have found it quicker to open a BPN because I have messed something up and then saved it. It is easier sometimes to open the BPN rather than trying to undo the changes - quicker to start again.
But each person has to weigh up their own data safety.
Some even frequently 'Save As' just to keep incremental backups of a project as it is being worked on.
Or you can get backup software that does all that for you.
I think even some cloud services keep previous copies.
Barry.
One of the forum moderators.
Versions 6.5 to 27
i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11