I’d like to back up the content on my MyCloud, what is the best option? Also, if I back uo to a USB device, does the usb device need to be the same size as the content being backed up?
It’s entirely up-to you and your circumstances.
I run an app daily on my PC to automatically mirror folders to an attached USB drive (SynchbackSE, there is a free version available)., takes a while initially , but once they are almost the same , the odd added file each day takes very little time to compare and copy over.
I also mirror to a second NAS using the built in function on my V1 to a V2.
And yes , it needs to be at LEAST the same size as the data being backed up,