[mythtvnz] Best Format for a 3TB?

[tortise]

Hi
Using Mythbuntu 10.04 I have attached a HDD to backup recordings to (to 
create space...), a recent 3TB drive formatted ext4 gives a warning that 
the partition is misaligned by 3072 bytes.  It seems healthy but is 
reported as largely full, however I am not convinced it is because a 12G 
file seemed to copy across still.
I'm going to format another, and maybe see what copies across.
The question I think I need to ask is what format should I use for the 
new 3T drive, however I am open to suggestions that I may not be asking 
the best question here!
In anticipation many thanks!