Take the IOPS do RAID6.....     The latency may not be all to related though....      Check to make sure cache is running properly on all your VM's,  make sure iSCSI targets are all what they should be.   Not real sure on Hyper-V but dell has there own MPIO drivers which could make a difference.   We are pounding our MD3000i's and never see 100ms, especially since going to vSphere. (esx 4.0)    
We have an MD3000i with 15 300GB 15K SAS drives. Right now we're just using 4 of the drives and running approximately 15 Hyper-V VMs off them. SAN is used for nothing else. One disk group with one LUN is where the VMs are residing. The VMs are nothing too intensive. Three (one dev and two production) SQL servers that are pretty low load, an Oracle development server with one person using it, two ColdFusion servers (one dev and one production) one or two IIS servers and my VMM server is running as a VM but  I might reinstall on a physical server. Anyways I consider my environment pretty low load and the number of virtual machines relatively low and I don't expect the number (15) to grow by much more in the future. Possibly we may virtualize our desktops in the future but probably they will be stored on another MD3000i or an MD1000. So to get to my point here what I'm getting performance wise. The top two charts are based on a 5 hour runtime during normal business hours. The lowest graph is currently what it is doing during normal business hours and varies a little. But not too much. Latency basically getting 100ms average. I've heard anything over 25ms is not too good. At least a review of the Solarwinds product said over 25ms was bad for a SAN. My IOPS figure I don't know if it's good or bad as we're pretty low load. Anyways my thoughts are my problems are the low number of spindles, it being a RAID 5 in a very high write environment, and only 1 LUN so only one controller is even being used. My thoughts are to make the SAN have two RAID 10's (using 12 disks) and maybe two LUNs per disk group. I don't like the idea of one disk group myself or big LUNs.  Thoughts?   [IMAGE] [IMAGE]   [IMAGE]
MD3000i performance...