I finally got my HDD upgraded to a 40GB, but the sales clerk gave us 2-1TB drives for the price of one. I was wondering what is the maximum size you can slap in a Xbox1. Thanks to Chimp 2.6 for letting me upgrade my HDD. (I don't have Hard-mod, I sucks at soldering)
you can have a maximum of 2 tera bytes, and for that one terabyte drrive format it using xbpartitioner, you have to format it using 64 kb clusters( i think better double check)
I have a 500GB in mine. Make sure you get the latest XBPartitioner, and set the cluster size appropriately. When I first did my drive I did the "F takes everything above the standard partitions up to 129GB \ G takes rest" scheme and the G drive ended up overwriting itself after it got >129GB full!