Das hier habe ich bei COPA gefunden:

You only need 2 thumb drives (not 3 or more). The charts, navdata, and obstacle data will fit just fine on a single thumb drive (for the CoPilot IFD). Engine logs can also be downloaded to the very same thumb drives.

My two 4GB drives are labeled and allocated this way:

Pilot IFD - NavData, Obstacle Data, Engine Logs

CoPilot IFD - NavData, Obstacle Data, Chart Data, Engine Logs

You do NOT need separate USB Thumb Drives for each product OR for the charts OR for your engine logs. One for each IFD effectively cuts your upload (data) or download (logs) times in half. Get some nice small ones and keep them in your flight bag in case you have to reload anything (or dump your logs) while on the road. 4 GB drives are cheap and readily available. Get ones that can accept a label or a keyring.