GNU parted is really user-hostile

[ewx]

(parted) mkpart primary 0 100%
Warning: You requested a partition from 0s to 5860533167s.
The closest location we can manage is 34s to 5860533134s.
Is this still acceptable to you?
Yes/No? yes
Warning: The resulting partition is not properly aligned for best performance.
Ignore/Cancel? 

As far as I can see the only way to discover what alignment it's looking for is to try ascending powers of 2 until it stops complaining.

gdisk seems to be friendlier and better-documented.