VM snapshot cosolidation with low disk space

Hi All,

One of our ESXI server datastore size is 500GB . this Host running 2 VM's with 320GB and 80GB. VDP appliance created snapshot and its not delete by VDP appliance . snapshot size is 75GB. but its growing fast. datastore free space is 82GB. how much free space required for succesfully consolidate this snapshot ?

Thanks & Regards

Lasantha.