I used to take a Netbook away on my travels, but it was quite heavy for hand luggage, had poor battery performance and needed mains to recharge it. I replaced it with a Samsung Tab 3.8.0 which is featherweight by comparison, has great battery performance and can back up my photos. I can also recharge it using my motorbike battery feed on bike trips and it seems to tolerate the vibrations without complaint.
Most modern tablets have a USB OTG (on the Go) capability, accessed by buying an accessory USB OTG cable. A card reader can then be attached and files transferred from the camera SD card to the micro SD card in the expansion slot on my Tab which takes cards up to 64 Gig capacity. A hard drive could also be fitted to the USB OTG cable, but needs the addition of a powered USB hub, the Tab does not produce enough power to power a conventional Hard Drive. I don't know if a Solid State Drive could be used without a powered USB Hub and of course, some Tabs and all IPads do not have a memory card expansion slot at all.
My tab also doubles up as a wireless remote control using the brilliant DSLR Dashboard App for my Nikon D3200 or the Lumix App for my GH3. I could also transfer pictures wirelessly from the Cameras to the Tab without a card reader, that would be slow and not all Apps support RAW transfers. Lastly, I have a Networked Wireless Western Digital Hard Drive at home which can supposedly be accessed securely over the internet, but I have never managed to get this facility to work, the set up arrangements are fiendishly complex. Most of the Hard Drive manufacturers offer something similar, so given better or simpler configuration and access software, it would be feasible to send photo files back to a home networked hard drive from any high speed WIFI connection in the world.