i have hyperv on windows server 2012 R2 running on a hp dl380 G8p with 2x 4core XeonE5-2620 smart array P420i with 1Gb BBWC and 80 GB of Server RAM
about 10 VMs running but some of them are extremely slow on the disk level.
in the VM the disk response times are from 1000 up to 7000 miliseconds while on the psycial level if i monitor the specific VHDX file it has 1 milisecond disk response time and 2-3 MB/s Total B/s counter.
The VM take ages to boot and responses very slowly to basic clicks. on the physical level all the counters seem to be very happy. CPU 3% MEMORY 80% Ethernet 20 Mbps. Disk response times 0-3 ms, disk queue 0,00-0,04. Nothing special really.
But within the VM (running MS Project 2013 which is bascially a sharepoint) i get crazy values for the disk performance. Other VMs at the same time do not seem to be in trouble. Only that one VM. CPU and RAM values are all fine
I have tried to use QOS for disks, dynamic memory or no dynamic memory (20 GB RAM), uninstalled antivirus but nothing is having a positive impact on the VM performance. The same behavior with the same VM was on the same physical server when there was windows 2008 R2 HyperV.
I start to think that i am experiencing some hyperV specific issue with that VM as this one http://support.microsoft.com/kb/2517329/en-us but as i am not on 2008 R2 anymore it does not apply.