Can someone explain how the Dell PowerVault MD3220i uses disk resources? I have 12x 931 GB (1 TB) disks in the SAN which should equal out to be 11,172 GB but instead the manager says total available to create arrays is 9,138 GB. Then after the array is created, it takes another 2 disks for overhead? At the end, the total available resources I can use to create my disk pools is 7,280 GB. We have 12 more slots available. What can we expect in terms of being able to expand what we have? Will we need to create another array? What's the formula of raw disk capacity to actual usable capacity in these units? Can I put dissimilar disks in the unit to expand? Would that force me to create a separate array?
I'm looking for best practice and the best path moving forward to increase the capacity of the SAN.