Redundancy with USB disk

Hi,

i want to build and easy and cheap home use NAS/Cloud therefore i probably go with RPI, a powered USB HUB and add some USB HDs.

My concern is about that the USB HDs could broke easily, and the data will be only in the nas, no other copies. Therefore i want to have the data in the NAS with redundancy.

Is this posibly with USB HDs to do some sort of NAS or is only for SATA HDs? (I don't care if the speed or the disponible space is reduced by this, i rather want to have security)

Sorry for any error, english is no my first language.

Regards,

PS: I'm open to another safe and cheaps configurations. Speed and size is not the main goal.

Thanks,

Although i'm not an unix fluent user, the rsync could be a nice options, ands allows me to have some folders with backup (my personal documents, photos and so on) and other that i don't mind to loose (downloaded files or something that i can recover) without copy and don't wasting duplicated size/duplicating resources. Also it can be programing to the hours that the system will be not used. I'm wrong in any of my asumptions?

I check de odroid-hc4 and will cost the same aprox amount that with the raspberry pi. It have any advantage? faster maybe becouse of ports used? more stable?

Also, with both setups could i acces to the hard disk from another pc in case of any problem?

Regards