Install the initial VNX rack with the DPEs and build/place the other two racks either to the left or right, but you can only build out additional racks in one direction.  The longest VNX backend cable length from DAEs is 10M, so allowing for cable runs from one rack to the next, it is not possible to build in "main" rack with the DPEs in the middle and then extend both sides.
I’m working with a customer to plan their data center layout for a new VNX. They plan to install a VNX that will ship with 3 racks on day 0. So the question comes up. What is the normal layout? Is the first rack in the middle with subsequent racks to either side or will controllers be on one side and additional racks growing to the other? Alternatively does it even matter?
How to plan Data Center layout for VNX