Hi Barry, The cables are not redundant it is 8 drives per cable. You could split the mirrors up like that but it shouldn’t matter, and will not provide a performance benefit. Our controllers do not support redundant controllers, so you cannot get a 2nd one and split the arrays between them. What is going on these VMs that requires this level of disk redundancy, but not server redundancy? Typically you can create a RAID 5,6,10,50,60 with all of the drives and use dynamically expanding VHDs for each virtual machine. 
Hi, I currently have an R820 with a PERC H710P & 16* 146GB 15k SAS disks. I was hoping comeone could help with with deciding what the optimum RAID config for 8*RAID1 Virtual Disks. The server is being configured with Windows 2012 Hyper-V  installed and 7 virtual Servers. Each having their own RAID1 Virtual Disk and one virtual Disk for the OS. A 16 disks are attached to the H710P Controller, via two cables SAS A and SAS B. The questions I have are; Are these redundant paths to the controller or are each of the grouping of 8 disks disks on seperate cables? If they are seperate paths then when creating the RAID1 Virtual Disks, should I be pairing Disk 0 with Disk8, Disd 1 with Disk 9 etc..or does this make any difference?  Also should I be considering a second Raid controller for redundancy? Or is it too late to change the configuration as suggested on p21 of the R820 Technical Guide pdf. Your help with these questions is very much appreciated. Thank You, Barry.
R820 Optimum RAID Configuration