Consistently out of disk space in docker beta

@b2jrock could you explain what the “scary part” does in detail? I got stuck at the second “2” as there was no such option…

Partition type
p primary (1 primary, 0 extended, 3 free)
e extended (container for logical partitions)
Select (default p): 2
Value out of range.
p primary (1 primary, 0 extended, 3 free)
e extended (container for logical partitions)
Select (default p):