I have a 2008r2 Hyper-v host with 4 Server 2008r2 guests. I am having problems moving data from disks on the host to the guests. Physically, I have 8 SAS HDDs in 4 RAID 1 mirrors. Each mirror has one of the guests. One of the mirrors also has data that is shared between the guests. If I try to transfer from within a guest from the shared space, I get less than 1Mb/s transfer rates. Going between guests is normal speeds and from shares on the network I get normal speeds. Pushing the data from the host to the guests is normal speeds as well. I'm only having a problem pulling data from within a guest. The server was configured with dual on-board Broadcom NICs. I saw all the problems people were having with those so I bought an Intel I210 NIC and am now using that with the Broadcoms dis-abled in the BIOS, the host OS doesn't even see them anymore.
I have been fighting this for several weeks now and have completely come up short. This system is used for processing data and the scientist that uses does not have access to the host OS.