This week I had a customer who was experiencing service loss on one of the VMs in their 2008 R2 Hyper-V environments. We initially started looking at disk as the source of the issue since the customer was using a Fiber Channel SATA SAN. I moved the LUNS into their own raid groups to assure each had their own spindles. I also converted the data drives to fixed length VHD files attached to the synthetic SCSI controller.
While these changes did drastically increase performance, the server would still have periods where it would “pause” for a second or two under heavy duress. Finally an error popped in the event viewer that gave us a solid lead.
The browser service was unable to retrieve a list of servers from the browser master \\PDCEmulatorName on the network \Device\NetBT_Tcpip\{SID}
Browser master: \\PDCEmulatorName
Network: \Device\NetBT_Tcpip_{SID}
This event may be caused by a temporary loss of network connectivity. If this message appears again, verify that the server is still connected to the network. The return code is in the Data text box.
For more information, see Help and Support Center at
The VM itself is temporarily losing network connectivity which is causing “pauses” during file activity. Microsoft has released a hot fix to handle the above issue. The hot fix needs to be installed on the host computer with the Hyper-V role. In this case on both 2008 R2 Server Core that comprise the environment.
The hot fix can be located here:
http://support.microsoft.com/kb/974909