Round the World Trip (storage advice)

Hello all,

I have been doing some reading/research but could use some advice.

In April I will be leaving for an undetermined amount of time. Could be 6 month,8 month, who knows. I shoot with a Sony a580 and usually shoot Raw or Raw+JPEG.

I am trying to think of the best combo for safely keeping my images.

How many memory cards should I take? 16gb seems to be the price break. Right now my 16gb card hold about 650 images if Raw+JPEG. I guess I could take 4-5 cards which would give me a lot of space. Eventually they will fill up though so I am thinking a backup HDD.

I know I can get a cheap external drive but I wont have access to a PC often. So do I do that which is cheaper or go with an OTG?

I know the Nexto seems to be popular. A little pricey thought at $300.

Any advice would be great?

Justin