Data store creation problem - need step by steps


I have 4 dell servers with 2cpu , 64Gb RAM, 150Gb ssd HDD and 5TB extra HDD.
I have installed open nebula 5.4 sun-stone on one another small acer server with 1CPU, 8GBram and 150GB HHD.
This sun-stone server have only 150Gb hdd storage. When I open Data store in sun-stone it is only sowing 150Gb size.
So I installed centos 7.4 and open-nebula KVM packages in my dell servers and added the hosts to open nebula through sun-stone GUI. but still there is no Data store showing. I have 5TB HDDs in 4 dell servers.
I want to use these HDD as data store to store VMs. I have tried to share these HDDs through NFS and software iSCSI. And I successfully mounted the Share in open-nebula server. Totally 5TBX4 HDDs I shared.
When I check the mount in open-nebula server back end using “df-hT” command everything looks good.
I mounted these shares in /mnt/D1, /mnt/D2, /mnt/D3, and /mnt/D4 directories.
But these storage spaces are not showing in sunstone GUI.
when I tried to create new Datastore from sun-stone GUI, every Data stores consuming space from my root partition (/ 150Gb).
I tried with NFS and iSCSi also. I mounted one of 5TB share on /var/lib/one/datastore, but not reflecting in GUI.

I have gone through the open-nebula DOCs it is totally confused. (
where should I mount these Space? on sun-stone server or individual host side?
on which directory?
Is there any step by step procedure to create new Datastore with local storage/NFS/iSCSI or any other method?

Please help