My environment consists of two FAS3140's in an Active/Active cluster and two DS4243 disk shelves. There are two quad port HBA's in each controller. As you can see from my diagram below, each HBA has two unused SAS ports. I'm adding a third DS4243 disk shelf and not sure if i should create a third stack or if this is even an option. Or is it best to add it to an existing stack? Any help is appreciated. Thank you.