I've got a disk performance issue in my HV cluster. I have 2 ibm x3850 x6's clustered running server 2012 R2 with and IBM XIV connected via 8gb fiber channel. When I run my SQLIO test from the host to XIV drive (CSV or drive letter), I get 180,000 iops / 1300MB throughput. When I run the same test from a guest VM with its vhdx on the same CSV, I get 30,000 iops and 250MB throughput.
My guest VM is server 2012R2 (gen2, fresh install). Where it gets even more interesting is that when I do a passthrough disk to the same VM, I get 90,000 iops / 700 MB throughput. Everything I've read online claims passthrough and vhdx should be very similar performance, as well as host and VM performance. There are no other VM's on the host.
Has anyone come across this before?