Extent Store

This is a concept that is used in the Nutanix Bible.  This is RAW capacity less CVM.  It represents the capacity that is available to a customer

 

Effective Capacity

Used in Storage Calculator or DesignBrewz.  This is the Extent Store * Storage Efficiency setting in  Storage calculator.  So if the Extent Store is 10TiB and the Storage Efficiency factor is set to 1.5:1 then the Effective Capacity is 15 TiB.   Storage Efficiency factor is the expected benefit of storage reduction approaches like compression, dedupe, ECX.  Effective Capacity then is what is hoped to be available with these reduction techniques