Presumably you formatted it in gparted too, in which case you might not notice a problem until you have more than 2TiB used.I partitioned it using gparted (using Ubuntu).
I'm not sure which format of partition able it used ... whichever is the default I suppose (I was going to look into that if it didn't work using the defaults). I could have a look at the settings in gparted to see what it's set to now - alternatively is there a way to check by querying the drive itself?
The same's true of the cluster size - presumably I can query the drive to see what it is...?
One way to check might be to run a file system check in maintenance mode. If it passes you should be fine but if it fails it might be this problem or a lack of memory. See the Wiki but I would suggest running 'e2fsck' with the -n option which will check the disk but not make any changes. I'm not sure how long it would take but it could be anything up to say 2 hours.