what is a Partition in A10 ??

I’m dealing with a TH1030S 4.1.1-P2 build 141 where I don’t see the 10G Ethernet 9 interface listed under “Create new VLAN” in a new partition I just created. Ethernet 9 is being used for other VLANs in another existing partition so I’m wondering if the issue I’m seeing is due to the ACOS version I’m running or something else. Any good info would be greatly appreciated.