If it is a one time transfer, plug them both into a PC ,set USB as file transfer then copy the folders over

Does this count ARMv6 256MB RAM running OpenMediaVault…hmm I have to fix my clock. LOL

Something like fslint might be what you want. Scan folders, lists duplicates, you set how you want to deal with them. Its more manual, but I think it is what you are actually trying to achieve.

Thanks, that’s a great write up

I guess in my case the batteries may have had enough to signal they were functional, but they were effectively dead and had no UPS backup sustaining power. One battery had started to buldge its container. I can see it as being an as designed feature, that way they never let you down in a powerfailure event, as you get advanced notice that the battery is no longer working LOL. Had a corporation go down a few years ago, they had not replaced UPS batteries, when power wentout all UPS batteries were dead and couldn’t sustain the servers until backup generator came online.

My CyberPower is 14 years old now still working fine, just needed battery swap at 10 year mark.

Haven’t had this happen. Battery pack failed after 10 years. Unit still provided mains AC through battery backup plugs. There is a switcher inside to flip between mains and battery…maybe that was going bad in what you describe.

Why not sata or nvme drives?

For a lot of applications the correct time may not matter but for something like homeassstant or syncthing you want your container time to be correct on a restart

You can set up one device to do masquerading and forwarding then you can see entire lan