Hi Bahmed! How are you doing?
If you have only one HA System and no switches, you'll probably want to follow the Switchless configuration for cabling on this document: https://library.netapp.com/ecm/ecm_download_file/ECMLP2316768
After the correct cabling you can decide between "physically" split your 24 drives in two, as you've mentioned, or having only one disk pool (data aggregate) to provide more spindles for better throughput.
In both configurations you'll have NDU if properly cabled and configured but, in one you'll have an active-passive architecture, with only one controller being responsible for all the throughput (you'll have more spindles in only one aggregate, a little more capacity ), in the other you'll both controllers acting as active-active (with less spindles per aggregate and a little less capacity).
In this library you'll find how to properly configure your system https://mysupport.netapp.com/documentation/docweb/index.html?productID=62343&language=en-US
