So I have a rather unusual and complex setup of computers. I have 2 homes, and spend equal amounts of time in both of them, and both have their own desktop computers. One has a 750GB SSD+1TB HDD and runs Windows 10 Enterprise, the other has a 500GB SSD only and runs Linux Mint 19. I also have a server, which has 2*1TB drives in RAID 1, with plenty of available space, running Ubuntu 18.04 Server. I also have 2 laptops: an HP Probook 455 G1, running Windows 10 Home and packing a 256GB SSD, and an HP Stream x360, with a 32GB eMMC drive running Linux Mint 19. Right now, even though I store some files in the cloud, I have no system in place for restoring system state should there be a failure.
My current situation and some of my thoughts are as follows
Important documents are stored in either Google Docs or Microsoft OneDrive, but not both at once.
Photos from my phone are backed up automatically to Google Photos. I've also organised some into albums, for easy access, and have backed up copies of some albums to Microsoft OneDrive. This leads me to my first question: would there be a way to automatically have the copy in OneDrive be updated, should there be changes to the one in Google Photos?
The first desktop computer, the one with a 750GB SSD and 1TB HDD, has a lot of programs installed, all with their own settings, and setting everything up again from scratch would be quite time-consuming. This is the main computer that I want to back up, all others are second to this. I'm thinking of using Windows System Image Backup to back up the entire contents of the SSD onto the HDD, and to prevent problems should the HDD fail, I'm gonna run File History backups on it. However, I'm not decided yet on where to save them. Should I use an external hard drive (I have old internal drives lying around which I can easily put in a USB enclosure), or use my server for this? If I were to use the server, I would somehow need to upload backups over the internet, as it is on a different network. Are there any such software solutions available, preferably free?
For other computers, the system state isn't as important, but I would still want to have a File History (or a Linux equivalent) solution set up. Are there any such programs available for Linux?
If I choose to back up to my server, should I make a backup of the server itself as well? Or is the redundancy from RAID 1 enough?
Any thoughts on this are welcome, and feel free to suggest alternative solutions to mine.
Huge thanks in advance.