why the Datastore Provisioned space is occupied in my storage pool

Hi All,

I have created multiple thin and thick volume in my 10 TB scaleIO Datastore. May i know why the Provisioned space is occupied in my storage pool.

It ll occupied only used space right? please confirm.

SDS with 19 Devices

Spare Capacity = 2.1 TB

Protected Capacity = 8 TB