usable storage

基本解释

The storage and the usable amount of soil water resource vary with the situations of meteorology, irrigation and crop growing.
土壤水储存量和土壤水可利用量随气象条件、灌溉以及作物状况不断变化；
The product is applied to transportation and storage of liquid nitrogen, liquid oxygen and other mediums. The adiabatic efficiency is excellent and the usable duration is long.
该系列产品用于液氨液氧等介质的运输和贮存，产品绝热性能好行用受命长。
www.bio-life.cn
The soil moisturegenerally is the state with low storage and low usability, all kinds of landremainds moisture potentiality in soil usable to the crops on the ground indifferent extent.
土壤水分一般处于低储量、低利用的状况，各地程度不同地保持着可供地面作物利用的土壤水分潜力。采取调整农林草的地区品种结构；

In the 64GB model, I suppose I can accept 45GB of usable space, but seeing the available storage of the 32GB model halved is downright egregious.
FORBES: It's Time For Windows Tablet Manufacturers To Advertise Usable Storage Space
It's not the only Android phone with storage space less than advertised -- visit our More Coverage link to see how the Droid RAZR Maxx's 16GB of storage magically transforms into 8GB of usable space.
ENGADGET