Why samba share folder' size is smaller than original folder?

I've used a storage with IP (10.10.133.50) and size is 10 TB. I have a server with static IP address (this server is same subnet with storage: 10.10.133.60) then I can mount the storage to the server with mount command. I can see it's 10 TB in the mounted folder. (Centos 6.5)

But when I used samba server to share this folder over Internet by static IP address like this. When I use Ubuntu client to connect to this network and mount with cifs, strangely I only can get 8 GB?

Here is the samba share config file. I don't want to reduce the size of the shared folder over samba, please help.

[storage]
path = /fimo_storage
browsable = yes
read only = no
create mask = 0777
guest ok = yes
writable = yes