I'm running Geth as well as Mist. I know I can run Geth, run Geth with console, run Geth and attach the console in a new terminal, as well as run Mist on its own. For some reason Mist doesn't seem to boot up when Geth is already running...
Either way, I want to do analysis on the live/main net so I want to download the full blockchain as well as have the fast version for transactions for when the full blockchain is not fully synched for a few days.
Is this possible/recommendable to do simply by specifying one of two separate data directories that I explicitly call when I run geth depending on if I want to update the full blockchain with geth or the light blockchain with geth --fast?