How is Kopia for backing up a working operating system… I’ve tried some others and always had issues with open files .
Thanks
Bob
Kopia is not for really meant for full system backup. It does not recognize certain file system features (fifos, sockets, block devices) and would not be able to precisely snapshot them in a way that can be restore back to a working system after at total loss.
For OS backups on Windows, there’s nothing like “Drive Snapshot” Drive Snapshot - Disk Image Backup for Windows NT/2000/XP/2003/X64
Also Clonezilla https://clonezilla.org/
For everything else, Kopia! 
I thought so but … it’s better to ask…
Thank you
Bob