Copied from a post I put on SoundOnSound previously: I use OneDrive extensively for storage / backup / sync.
The sync tools occasionally 'lose the plot' and may need time (or tinkering) to get them to sync again, but mostly it's very reliable.
I don't use OneDrive sync on the primary Sonar folders (they change a lot during music sessions, and the sync tool is constantly trying to keep up).
My 'sonar' login doesn't have OneDrive running (I try to stop all non-essential services), but at the end of each session I copy the relevant folders from my Sonar project folder over to one of the folders that are sync'd by OneDrive (under my primary user account). I then log in as my primary account and leave the PC running for a while to sync to OneDrive (getting my work offsite as quickly as practically possible after the session finishes).
I take local backups (approx. monthly) of all data to USB drive (and store at work) to provide 'point in time' historic, offsite backups (and also mitigate against any issues with OneDrive.
The only risk left is Malware (in particular Ransomware) - if this hits then it is likely to sync the infected / encrypted files to OneDrive before I know it's happened. The offsite (monthly) backups help against this, but that could be a lot of work (up to 1 month) to lose....
So lastly, I have a secondary drive in the PC that is only accessible by a specific 'backup' user (and it's encrypted with BitLocker). Weekly (or more often) I login as the backup user and XCOPY all my data onto the secondary drive.
So I have (almost) real-time backups to the cloud, weekly backups to an onsite backup, and monthly backups offsite.
Paranoid?? - Probably....
https://www.soundonsound.com/forum/viewtopic.php?f=20&t=49440&hilit=onedrive&start=25 Added to that, I've since found another option. With Office365 Home you get 5 users - and I'm only using 2 (me and the Mrs) - so I've created 2 further accounts as 'backup' accounts (with different email addresses and passwords). You can then use a free online tool like MultCloud (
https://www.multcloud.com/home) to copy my entire OneDrive to my 'backup' OneDrive (this is all done in the cloud and doesn't use your PC or internet connection at all).
Again this occasionally has issues - mainly with open files (such as OneNote which may be running on my phone) - but is another great way to keep backups (and make use of the 'free' storage from my subscription).