Comment 1 for bug 1681658

This is the correct behavior. min_unit and max_unit describe the minimum and maximum amounts that any single allocation must fit within. However it's not entirely clear if that describe your case as you've not said what your inventory settings are.

Assuming your max_unit is <80 then that means an 80GB allocation is not possible, whatever allocation_ratio is set to.

What allocation_ratio does is modify the apparently available total capacity for all all allocations.

max_unit is the biggest any single allocation can be
step_size is the "chunk size" of any allocation. For example if '5' any allocation must be a multiple of 5 and:

* more than min_unit
* less than max_unit
* and within the remaining capacity where capacity = ((total - reservered) * allocation_ration) - amount already allocated)

Please follow up if this doesn't explain things.