This question already has an answer here:

The question is simple though I can't find a solution to this - how do I keep all ethereum-related files on an external hard disk drive?

I would like to have the blockchain data, keystore and Mist launch files to be on an external HDD that can be easily moved/connected to another PC etc.

merged by eth May 30 '16 at 9:00

This question was merged with How to set a different datadir in Mist? because it is an exact duplicate of that question.