Hello emcmagic. Ok. let me do my bit to try and get this across to you. If you look at the #symdisk list output you'd see directors labelled 5 to 12 .. which is a total of 8 back-end directors spread across 4 engines, for your 4 engine VMAX. Drives connecting to directors 5 and 6 are located on an engine, Drives connecting to directors 7 and 8 are located on an engine, Drives connecting to directors 9 and 10 are located on an engine, Drives connecting to directors 11 and 12 are located on an engine.  A small correction to what I wrote on the previous reply : For example - 5A is a (back-end) director .. 5A:C is cabled to 1 DAE (the same DAE is connected to director 6A:C (using LCC B -- remember that the drives are dual ported for backend redundancy) -- directors 5 and 6 are located within the same engine) and 5A:C6 is your EFD within the DAE. [Note: If it were a DMX, the DAE would have cables coming in from director ports 5A:C and 12A:C]  If you look at the figure below .. Each engine with it's 2 back-end director ports connect to 8 unique DAEs (which is why the name "octant") .. for example - back-end directors 5 and 6 on Engine 3 will connect to 8 DAEs on storage bay 1B (Octant 3 in Orange color) using direct connections. The 8 connections to the 8 unique DAEs (from LCC A) will be 5A:C, 5A:D, 5B:C, 5B:D, 5C:C, 5C:D, 5D:C, 5D:D. The same 8 DAEs will have a connection from the redundant backend directors ports of director 6 from LCC B. (6A:C, 6A:D, 6B:C, 6B:D, 6C:C, 6C:D, 6D:C, 6D:D)  [IMAGE] Do take a look at the complete output from a #symdisk list (not just disk group 3 which is your EFDs) ..  I'll paste a DMX back-end architecture to help you visualize this better ..  [IMAGE]  So if you look at the back-end [directors labelled DF01 and DF16], a DAE is cabled to dir port 1B:C and to a redundant back-end port 16B:C. So these 2 director pairs can connect to 8 unique DAE's. (1 and 16 work in pairs, 2 and 15 work in pairs and so on .. for a DMX) Similarly for a VMAX, you have directors within an engine working in pairs, connecting to 8 unique DAEs using 8 director ports. (1 and 2 work in pairs.. 3 and 4 work in pairs .. so on). Hope this helps.  thanks.
I have VMX-20 and with 4 engines. Further, it has EFD, FC-15K, FC-10K, and SATA drives, with FAST VP configuration. Can you please share with me the rule/best practice of how these drives should be spread, and to what engines/directors, and what commands to show me the layout on what drives are located in what engines / dirs.  Thanks!
To show the layout of what engines and dir where each different type of disks 
is located?