Please note that dg01 and dg02 both are actually Virtual Disk Groups (VDG) but you have presented volumes which you have created from Pools.
In MSA2050 the architecture is couple of drives create VDG. All VDG will be part of Pool A or Pool B depends on Controller A or Controller B
You might have created Thin Provision Volume of 4900GB
So if you have deleted some VDG which is dg02 in your case that will decrease space from Pool but Volume size will be same only until you modify the same manually.
Your Windows 2016 can't see VDG. Host systems only deals with volumes.
Hope this helps!
Regards
Subhajit
I am an HPE employee
If you feel this was helpful please click the KUDOS! thumb below!
***********************************************************************